Immunology Transcript - Transplantation & Immune Pharmacotherapy PT. 2 PDF

Okay, so last class, we left off with transplantation. We were talking about just how in general, as you guys can imagine, anytime you get cut open, there's a lot of trauma, there's a lot of inflammation. I can already predispose you to have consequences of that. But it is really important when we'r...

Okay, so last class, we left off with transplantation. We were talking about just how in general, as you guys can imagine, anytime you get cut open, there's a lot of trauma, there's a lot of inflammation. I can already predispose you to have consequences of that. But it is really important when we're going through two to limit that risk as much as possible. And one way we can do that is by finding as much matching between the two individuals as in the donor and the recipient as possible to prevent all the different types of rejection here. And so this is just showing you that anytime you have any kind of HLA differences between the transplant donor and the recipient can activate numerous self-reactive T cells here. Because again, if there's slight differences again, it's gonna notice that, recognize it, mount a response, and we're gonna have some issues here. And so it is also important to make sure that when we have that matching, think about it. What is the importance of knowing, well besides autoimmune, of knowing self versus non- self? We can attack foreign, right? So what if we are transplanting certain organs and there are other dendritic cells and things like that in there that don't recognize, they recognize foreign but they don't recognize self enough to be able to present foreign to self. We run into other risks where we're immunosuppressed technically because our cells aren't able to communicate with each other because there are too many differences that they're speaking foreign languages. And it's like here, they're trying to say, hey, this is a bad guy, you should do something, and they're speaking Finnish. And does anyone in this class speak Finnish? I use that because every single year, the example I use, someone ends up speaking some language that I didn't think anyone in the class spoke, so Finnish. And so if you have that, you can't communicate, we don't have Google Translate, part of your immune function is gonna go down too. And so it is really important too that we go through this matching. And so this is just reminding you, this picture on the side seems overwhelming, but again, it's just talking about the fact that we do go through positive and negative selection so that our T cells are very prime to know what self and non-self is because one, we needed to know what self is so we don't inappropriately attack it, especially helpful when we get transplantation, we want to be able to communicate and not recognize that as foreign and attack it. But also we need to be able to talk to those tissues too because if there's an infection in the happy little dendritic cells and our new transplant and kidney are like, hey, like this is bad, like you should do something. And they're just, it's whale sounds. None of you guys speak whale, I can be very certain of that. Some whale sounds and you cannot talk like as much as Dory tries, you can't speak whale. So that is also a risk that we need to think about there too. And so basically all it is is just reminding you of positive and negative selection just because again, our T cells go through extensive education of what is self and non-self. So that was the main takeaway of that slide here. Something we can do, say we have a little bit more time, say it is a patient who's been comatose for a while, the patient's family makes the incredibly difficult decision to end life support. And so you have a little bit more time to do matching. It's not like an immediate traffic accident where you have to do a transplantation now, it's a quick match. If you have a little bit more time to go through testing, there's an additional test that we can do called the mixed lymphocyte reaction where if we have time to do this, we can take both the patient and the donor cells outside of their body and mix it and grow it in culture just to see how well they play together outside of the body. That way there's no risk of rejection, there's no risk of any damage, there's no risk of eventually triggering any kind of reaction. We're testing it in a culture just to see what happens because in a mixed lymphocyte here, we're also gonna measure proliferation because proliferation can indicate that the cells are becoming activated and therefore dividing. And so we'll look at proliferation but we can also measure cytotoxicity. We want, are they becoming proliferating and expanding here or are they killing the cells? If we start to see cytotoxicity, it means they don't play well with each other. We should probably not do a transplant because there is a higher risk of rejection. And so we'll just culture the cells together and after three or four days, we measure that here. Proliferation is just seeing how alloreactive are we, how well do they respond and play with each other here and dividing here and then killing obviously is a direct measurement of how likely and how quickly we'll have graft rejection. It is not a perfect system though. It is a little, you know, an extra step in the protective testing that we do. It's not a perfect system because as we've mentioned before, there can be some delayed rejections where it's just over time, you know, gradually your body starts to slowly reject the tissue. This obviously three to four days is not enough time to truly measure a delayed type rejection but it is better than nothing. So if we have time to do HLA matching and then actually even do this mixed lymphocyte reaction, we can say with some fairly decent confidence that there is a less likely risk that we'll reject the tissue, especially very quickly. This is showing an acute rejection and acute rejections fall under type four hypersensitivity because it's caused by T cells. So they can be a little bit delayed. We'll talk about with Nate. However, the most part we see delayed as being kind of over two weeks, but every once in a while, you can see it happen a little bit faster than that just because it is defined by its T cells specifically triggering that type of rejection here. This is just showing you an acutely rejected kidney so remember, hypercute is super fast. You know, within like a week or so, the body is just not tolerating it. Something bad is happening. Acute can take a little bit longer than that. But what you'll start to see typically large, I mean, granted there will be bruising with surgery but you'll see even more swelling, bruising, hemorrhaging too. And if they look at the tissue, you'll start to find black spots of necrosis because again, if you have hemorrhage and blockage of blood vessels, you're not getting oxygen and other nutrients to these areas. The tissue starts to die and it becomes necrotic. At this point, surgeons will need to go back in and remove that tissue because if necrosis spreads, obviously that's a bad thing. Every once in a while, you can transplant a kidney. It works like especially the ones where it's not critical. You have like two of them, other things like that. Where you transplant one kidney, it doesn't work. They remove it. The patient still has to go on dialysis but they still have at least one functioning kidney. It's not a perfect system anymore but at least they're not massively rejecting, causes massive inflammation which could potentially spread and kill them. So, transplantation is a huge field and there's lots of different aspects that you guys can go into it if you want to overall. This one's showing an acute rejection of a kidney graft through the direct pathway of allo-recognition here. So it's just talking about with self-recognition here. And so a dendritic cell in the kidney graft area of the donor here travels in the blood to the spleen where they activate the recipient's T cells here to let them know, hey, we found this here. Allo-reactive T cells can leave the spleen and travel to the blood, to the allographic kidney and attack and cause massive amounts of damage. So what it's showing here is that inappropriately, those dendritic cells are of the donor. They travel in the normal immune process that we should expect them to do. They're doing their job but they're traveling to the recipient's secondary lymphoid organs and inappropriately presenting self-antigens. And because if you have minor differences where it's similar enough but still different, it will trigger those T cells then to start attacking self. And like in this case, it's not really self, it's the donor's material. It's similar enough so that it kind of resembles self but has some changes to it too. And it can mount a massive rejection because again, the T cells are going to this area rejecting the donor tissue, but can again expand off because this donor tissue has some foreign antigen and some similar. So say hypothetically Sabrina and I are fraternal twins. We have similar enough-ish DNA but there are some differences. She so kindly donates her kidney to me because I'm an idiot and somehow got rid of a kidney. She donates a kidney. It's similar enough that the body still recognizes that we are related, but there are still differences. It still recognizes that something is different. And because of that, now the T cells are activated to this new tissue, but in the accidental consequence of they're responding to the foreign stuff too but can also inappropriately start responding to the foreign with the stuff that kind of resembles my DNA too. And so again, the risks of that is if we leave that transplanted organ too long, especially when we have that alla rejection, those T cells can spread out and start attacking other self-tissue by accident just because it's like, oh, well this was self with some foreign. We're priming and responding to this but now we're gonna start just widespread attacking self. And so it's kind of a spillover effect almost with that. But when we have it directly attacking that specific tissue that we donated or was transplanted in, we will have that rejection and it is critical to then remove said tissue. When we talk about a chronic rejection, which as you guys can gather, takes a little bit longer. This can be years after the fact of rejection. Most people argue that at some point you will have rejection, which is why if possible they do also try to delay transplants if they can a little bit longer. But again, it's dependent on proper matching too because again, think about if you get a transplant at 15 and you lived to 70, that's a lot more years that your body can build up rejection to something versus if you're already in your 70s or probably 60s or so, you have a little bit more life to live rejection at 15 years from then you might be closer to your death bed and then a 15 year old who's almost 30, 15 years later. When we're talking about chronic rejection, it is equivalent to a type three, which is mediated by immune complexes. So this is not cellularly directed. These are antibodies being produced against the transplanted tissue and causing inflammation here. And so when those immune complexes will be deposited on blood vessels within the transplanted tissue, obviously we know that that FC tail is wiggling. It's attracting phagocytic cells from the recipient to the tissue, binding on triggering immune response, inflammation, things like that, recruiting more immune cell types. And so when you have damage to any of the blood vessels, again, leads to inflammation, decreased blood flow, hemorrhage, risk of rejection there too. We do have both direct and indirect pathways of allorecognition that can contribute to graft recognition here too. So you guys already know if it's direct, it means the cells are directly binding onto a T cell and activating it. So if a donor dendritic cell is directly presenting antigen to a self CD4 or CD8 T cell, it's direct. There's no middleman. But you can also have it where a donor cell, just during the process, the surgery, even a little bit of time later, dies naturally and macrophages, recipient macrophages or dendritic cells come in and gobble up that DNA, or not the DNA, the DNA, the cells, all that fun stuff, presents those antigens on the surface. They can activate CD4 T cells to then start going in and rejecting the tissue. So again, direct is just straight dendritic cell to CD4 or CD8 T cell. Indirect is one of the antigen presenting cells directly to a CD4 after gobbling it up. And so there's like this extra step involved with this process here. And so does that make sense? Everyone comfortable? Direct is just the fastest way possible. Indirect is an extra step involved. By definition, a type of alloreactive reaction within a direct pathway in which T cells as a recipient of a transplant are activated by direct interaction of their receptors with the allogeneic HLA molecules expressed by those dendritic cells from the donor and present in the transplant. So they're directly responding to those self molecules on those dendritic cells versus indirect is gobbling up cells from the donor, presenting it on the surface to T cells and activating it. So one means by which alloreactive T cells in a transplant recipient can be stimulated to react against the transplant. The alloreactive T cells do not directly recognize the transplanted cells, but recognize subcellular material from these cells that has been processed and presented by the recipient's own dendritic cells here. And so again, that's just showing you that pathway here. When we have that indirect pathway of allorecognition, it is responsible for stimulating the production of those anti-HLA antibodies that can cause those chronic graft rejection. And so you guys already know this process here. The alloantibodies that cause it are from this pathway here with indirect because what's happening here is say we have donor cell debris that has HLA class two on there. Dendritic cells are gobbling it up, presenting it on the surface here by non-to-bet CD4 T cells. This is like the summary of the whole semester right here. That CD4 T cell is also presenting antigen to that B cell here. Same thing, it can also recognize some of that debris here as well and present it to the T cell as well because remember you need antigen activation with the B cells first to be like, hey, we're responding to the same bad guy. In this case, it's not a bad guy, unfortunately. We're just rejecting it. Thus leading to activation of that B cell which will then now lead to antibodies that can directly bind onto those human leukocyte antigens recognized in that donor tissue. And so obviously if eventually, and this is why it's chronic, we know it takes a while for the adaptive immune response to kick in to start going through that process, producing antibodies, all that fun stuff. That's a lot of time shown in this picture here. That's why chronic obviously is named chronic because it doesn't happen immediately. It takes a little bit of time to pick up for us to have the response, but eventually it is due to those antibodies binding onto that anti-HLA that it's now being produced against and triggering an immune response and rejection here. So this is just a good summary of the various ones. I've put it into bullet note PowerPoints like say the day before the exam, you're panicking and you didn't study this. I won't say this will get you an A on this section, but it will at least help you narrow it down pretty quickly. But if you wanna compare it pretty close just because it is a lot of information, it is right here. Obviously chronic, well-named, it takes the longest here. It is the slowest and least vigorous type of rejection because it is due to those antibodies. And so with this one, we frequently have a vascular connection established. It's building and it's like when you plant a tree and the roots start growing out into the environment. Same thing here, it's growing vasculature with the host, it's establishing. And so it can even happen for weeks, months, years later before we start to know the signs that we are starting to reject it. And so after the first signs of rejection, destruction will proceed very slowly because again, it's antibody mediated. Sometimes we can control it with immunosuppressants and monoclonal antibodies to kind of suppress antibodies to the HLA. But again, that's very targeted. But the reason it's really slow too is as it's attacking there's that fibrosis and that inflammation is just kind of causing scar tissue within the transplanted organ. And so eventually it becomes just kind of all, I'm gonna keep pointing to kidneys, it's gonna basically form all scar tissue and eventually it's not functioning anymore and we have to remove it overall. And so this is more typical in situations where the donor and recipient differ by only non-MHC histocompatibility gene differences. Again, we talk about mostly those main classic MHC2, HLA. But you guys remember we had those non-classical subtypes. There are minute sub differences that can trigger rejections and that's again in chronic because they are tiny, not the big guys, but little non-classical ones that are still different enough, the body eventually responds to them. With acute, obviously this occurs much sooner after graft emplacement than chronic. We do typically see vascular connections establishing so that the tissue is at least trying to build its way into the body here. But again, it is usually a relatively short period. So typically under a month and then we start to see signs of rejection here. However, once it starts, because this is T-cell mediated, it progresses very rapidly. And so this one is more critical that with chronic, sometimes we can do immunosuppressants, try to just delay it as long as possible. With acute, this frequently means scheduling a surgery to remove the transplanted organ because eventually we will reject it very quickly here. Because the grafts become edematous and inflamed, so massive and swollen. We'll see all kinds of blood and mononuclear cells and typically massive tissue destruction, which can eventually spread. So it is critical to go in and remove that. And with this one, it's commonly seen when donor and recipient differ at MHC histocompatibility genes, especially if we're involving class 1 MHC or class 1 HLA, BLOSI. And we talk about hyperacute, this is the most rapid. This is within a few days of graft placement. There is no time for vasculature to form. And with this one, it's immune attack typically directed at the vasculature of the graft that's going after the blood vessels, really destroying it. We see complement pathways activated, natural killer cells activated, even preexisting antibodies. We call these guys white grafts because it was named after, it's very more obvious to see with skin rejections because when you have it, like say you do, you got a burn on your arm, they took skin from your leg, put it on your arm. When that tissue dies, it turns bright white because there's no blood flow to the area anymore. And so they call it a white rejection. However, it's kind of a misnomer because if it's inside your kidney, like it's inside your body, and I can't see inside of there, I can't tell you it's white. If you go to remove it, you'll see that it's white. But so that's why I'm like, its nickname is a white graft, even though it's only useful with the skin. You can't really see if it's internal, but it will turn white because it is losing blood for that here. With kidneys though, obviously when the blood builds up and you just get like fluid buildup, blood buildup, DMA, things like that, it can become bluish though. Like obviously when you lose oxygen, it becomes blue. So again, that's why I think white grafts is misleading, even though they frequently use that term in discussion overall. Unfortunately, unfortunately, unfortunately, we love immunological memory. It doesn't work so great with transplants though. Because if we transplant a kidney, Sabrina's so kind, she gave me a kidney, fantastic. It didn't work. I really want her other kidney. It's not gonna happen now. I now have an immunological memory that I rejected that first kidney. A second one from her is not going to work. And probably say hypothetically, we were three fraternal twins. And there was a third one, Ellen right behind her was also one of our triplet fraternal twins. Guarantee, Ellen has similar ish enough something to the two of us, that more than likely I would probably also reject Ellen's because I already mounted a rejection to Sabrina. I recognize self enough, but also the non-self enough too, that unfortunately I'm probably not eligible for anyone even remotely similar to Sabrina for a transplant, which can really be unfortunate overall. And so again, attempts to repeat are frequently rejected just because we have immunological memory to it now. A lot of people won't even risk doing that second one just because it's known as a second set rejection because we'll see it. And also too, we do notice that it tends to get faster the second time. So say it was chronic the first time and eventually we did have to remove it. We went to do a second one, more than likely that second rejection is going to be acute. Or if we started with an acute rejection, we tried it again, it's probably gonna be hyper acute. And so unfortunately it does speed up with which we respond to these infections, unfortunately here. But I forgot to bold this right down here, but it's bolded here. The definition of a second set response is a secondary immune response directed against histocompatibility antigens, transplant rejection overall here. Do not have to memorize this chart, this is just some fun stuff because they have gone through to try to figure out, like there's all kinds of mathematical algorithms to predict the best possible outcome with transplant patients here. And so based on the number of mismatches that you have overall, we can give you a rough 10-year estimate and this does vary depending on tissue too. And this I think was in kidney grafts overall. But about 33% have a 10-year estimate of not rejecting at that point, which is nice. It gets a little bit less as you go further on, you're more likely to reject it if you have more and more mismatches overall. And the half-life is a rough estimate in the mathematical times of like how long a patient will live without rejecting after they've had the rejection overall here. So half-life often with these guys here is about 8.9 overall. And again, this is an average of this. But it's better to have more matches than not enough matches too. And so too, we do try to control for this as much as possible as we're going through this process. We do use immunosuppressive drugs for both the patient and the recipient to try to suppress the immune responses before we transplant here too. And so it does allow it. Kidney transplants are one of the most common we do see in the United States because thankfully we all have two kidneys. And so you can still function with one kidney, especially if you're healthy. And so a lot of people do try to donate kidneys overall. And so they do give immunosuppression before and after kidney transplantation because again, you don't want it to be primed in an inflammatory state before we do the transplant. And also you want to keep it somewhat suppressed after. Some patients are pretty much on low levels of immunosuppressant meds pretty much for the rest of their lives. Because again, it's trying to suppress the immune response as long as possible. But again, it's a big discussion for you to have with your patient because what are risks of being on chronic immunosuppressive drugs? Your susceptible do everything else. And so it's also discussing their lifestyle factors with them. Like do they have riskier behaviors where they're more likely to contract other things? Are they an intravenous drug user where they're more likely to contract and they don't use clean needles? Where they're more likely to pick up other viruses? That could take them out a lot faster than if they try to work out, maintain their weight, exercise, drink lots of water, stuff like that. And so it is a big discussion with your patient on what their overall risk is, not just for the rejection, but also their lifestyle changes for the rest of their life. So it's a loaded, loaded field overall here too. And so this is talking about one of the different drugs that we can use. We have one known as anti-CD-52. It's an antibody against CD-52. And it is effective at depleting leukocytes before organ transplantation. So this is a frequent drug that we'll use. I'm not gonna give you all the fun drug names. Just know it's an anti-52 mechanism here. But basically it helps fix complement on leukocyte surfaces and triggering phagocytosis here in general. And so, sorry, CD-52 is efficient at binding. When you have anti-CD-52, it blocks this. And so the antibody to it prevents complement really from binding CD- 52. The anti-CD-52 is brought close to cell surface, increasing the likelihood that C3B is produced, which leads to the binding of the leukocyte surface. So we do use anti-CD-52 to target and deplete macrophages and other phagocytic cells before transplantation is one of the different drugs. Although you typically do a combination because we'll also do nonsteroidal anti-inflammatory to suppress as well. And you can also use full steroids too. So you guys, have you guys had steroids yet with MPP? You get steroids next semester then, I think. We used to line it up where steroids did match up with this, but I think immuno is a little bit easier taught in the first semester here. So are you guys at least familiar with steroids? Like you've had them in the past, you know that they like, or corticosteroids or like asthma inhalers or steroids, things like that. What do they do? Oh, she was going into the, no, we don't want to know. What's the shorthand version of the biomolecular pathways? What do they do? Suppress inflammation? Yeah, yeah. That was great though, I love that. I don't like, I don't like anything. Dr. McClellan, who's the other immunologist, we were joking outside of studying this office. We were like, we hate biomolecular pathways and intracellular stuff. We like what happens when it releases the cytokines and all the extra stuff. We don't care about what's happening inside of the cell. That's all Dr. Steading. But I thought it was funny that most immunologists, I talked to her like, yeah, we don't want to know. It goes on inside, we don't know the consequences outside. But they are, oh, well, there's lots of definition here. I would know the definition for the exam because it's bolded. They are lipid soluble compounds that diffuse across plasma membranes and bind to their receptors inside us all and modulate transcription of a wide variety of genes here. But in general, steroids decrease inflammation. If you ever had a steroid shot with an injury, steroids, ooh, COVID or upper respiratory infection, your lungs are really inflamed and like you're having a difficult time breathing. They'll give you steroids to help you breathe. They're like the nebulizer. When you breathe into steroids to help suppress, you don't have to memorize this top picture if my rant and tirade about intracellular stuff was not a dead giveaway. I'm verbalizing it right now. I don't really care. Appreciate it, I don't care. So therefore it's probably not gonna be on the exam as in like, it's not going to be on the exam. But they do cross the plasma membrane because they are lipid soluble, which means they can cross that lipid bilayer, get inside and they exert their effects typically on the nucleus. The big picture, they lead to decreases in inflammation, which is great because if your body's already inflamed, it's looking for, you know, you have more immune cells, it's looking for trouble. And so if we can suppress that before doing a transplant, it's fantastic because we do increase the likelihood that hopefully it will stick overall. Do not memorize this. Appreciate that science has figured this out. You guys know some of these guys though who remembers TNF alpha. Proinflammatory, so if we have an arrow saying down, it means we decrease the proinflammatory stuff, it's great. And so there are various other molecules that we can suppress. You guys know nitric oxide synthase, it's one of the reactive oxygen species. There are various drugs that we can do to suppress those here, but in general, this is what your corticosteroid therapy is doing. There are lots of different mechanisms and lots of different drug pathways. Skinner knows all of them, you should ask him about it. Don't ask him, he's gonna be mad. Oh, I didn't give him a morning here. But how they work in the system, they reduce the production of inflammatory mediators like cytokines up here, prostaglandins. You guys know prostaglandins eventually lead to what? Beaver, warmth, inflammation, all of those, as well as nitric oxide, so those reactive oxygen species here. By their effects on other cytokines though, they will also decrease synthesis of IL-2, which means they're limiting the activation of lymphocytes, which is also nice. We kind of want to suppress those as well too. They do prevent the migration of inflammatory cells and other molecules to the area by hiding those adhesion factors and suppressing those. Those cells need to be attracted to certain regions and kind of roll and enter into those cells and that diapadesis should throw back to module one. And they can also in certain instances promote to apatotic death of certain leukocytes and lymphocytes. So there's a lot of different drugs out there available. Obviously, if you're doing a transplantation, it's frequently on heavy cocktails of multiple different drugs because you're kind of taking out everything if you can. So we can, again, suppress that T-cell activation by alloansions by providing those immunosuppressive drugs to suppress various aspects of the immune response so that we're not going to inappropriately bind on an attack. Do not panic. I highlighted just the parts that I want you to know. If the pictures help, I included the full information here, but the two drugs that we frequently use with immunosuppressants and when we're doing transplantation is cyclosporine and tichrolimus. And both of these guys work to inhibit T-cell activation by interfering with serine, threonine, phosphatase, calcineurin. That is a fact here. And so it just adds a little bit more detail here too. Both of these guys interfere with activation of AP1. Have you guys talked about that with biochem at all or MBG? Nope, don't worry about it then. So this leads to binding to FK binding protein or FKBP and the complex of these guys here will bind to calcineurin blocking its ability to activate NFAT. A lot of molecular, like who named this? I really want to know. I want to be like a fly on the wall when someone came up with these abbreviations. And tichrolimus will block that FKBP blocking its activity. So the big picture takeaway is up here, which I think is more important. If you guys are nerds for biochem and molecular processes, I kept this thing here in case it makes sense to you and you want to figure it out. This is a bunch of, who knows? This is finished to me right here. But anyway, it's blocking transcription, which eventually blocks that production of IL-2. We know IL-2 is involved with lymphocyte activation, which is why both of these drugs in the big picture circle back, inhibit T-cell activation overall. We block those cytokines. So I wanted to make this easier. Breed it once, appreciate it. Moving on, we know cyclosporine and tichrolimus inhibit T-cell activation by interfering with the serine, threonine, phosphatase, calcineurin. Boom, memorize that, we should be good. And then you can just impress Dr. Steading later when you quote that directly to her and she's like, oh, you learned that whole path? No, you didn't. It's totally fine. This is a bigger picture of, notice how these are very small. I zoomed them in in case you wanted to see the visualization of it, so it's an extra slide that you already saw, and then here's the second half. And notice, these two are identical to these two because it wanted the picture, I'm sorry, these two, because it wanted the picture to be consistent. So there's two extra slides you don't have to study because you took away the big picture here. But I included it in case it helps you understand those here. Additional effects of cyclosporine and tricholimus, we know it really does work on T cells here because it reduces the expression of a lot of these different cytokines with most notably that IL2 here, but because of that, it will decrease cell division. And can we think about it like T cells work with B cells, right? And so do we expect that if we're affecting T cell activation and division, do we think we're also gonna possibly have downstream effects with B cells? Yes, and so we can see inhibition of cell division with this because we're missing those T cell cytokines that we need to help activate B cells. Obviously, it can inhibit cell division overall here. And in some cases, it can actually induce apoptosis of antigen-driven B cell activation too, which is pretty cool. They have also gone back and found these drugs also do have effects on granulocytes, like your neutrophils, esemophils, vasophils, and your macrophages too, because they did go back and figure out that it decreases calcium-dependent exocytosis of granules. So basically, it's preventing degranulation overall. And degranulation is that critical feature with innate immune system. And so again, we're suppressing it in multiple aspects with the hope that these two drugs in combination can decrease the new recipient's response from the surgery and this new transplanted organ, and hopefully prevent rejection here. No, I will not show you a picture and expect you just to identify the picture alone. The picture might be seen in supplementation with a question stem. You guys are not pathologists yet. And so that is not a fair question. However, I do think they're pretty pictures. So you might see one tossed into a case study. It's not critical to be able to solve a case study by itself here. This in general is just showing you in a kidney. We are seeing arterioles kind of building, or I'm sorry, lymphocytes building up around an arteriole labeled A here inside of a kidney undergoing rejection, which is pretty cool. And then you see the same thing. It's building up around a tubule identified as a T here. So having increased cells load in here to reject. We're having increased immune infiltration overall here too. And then again, this is DAB staining where we can only stain one marker here, but it is showing CD3. CD3 is found on what? All T cells. And so all of this brown stuff in here in the same section of tissue is showing that you have an infiltration of all of these lymphocytes to this kidney as we're undergoing rejection here, which is kind of cool that we're able to actually pause it at certain points to get the histology and stain it and see here too. Serum sickness is a slightly different type of rejection. It still falls under rejection here. This is obviously a very severe case of it. Your textbook likes to pick really, really severe pictures of this here. Serum sickness is a classic example of a type three hypersensitivity. Nate will talk about this a lot more with different types of drugs next week here. But what we see with this, it's, we see it's serum sickness because they're saying it's affecting the blood, which is why you see this purpura and the rash and stuff spreading throughout the body here too. But it's due to antigen antibody complexes building up after intravenous injection of a drug. Frequently, we see this surprisingly, I never would have guessed this, with like anti-venom and antitoxin that we get for like snake bites. People can oftentimes have a risk of that. Obviously, if you do too high of a dose, you're more likely to trigger a reaction so you have a very high amount of it here too. And so, especially if you're doing intravenous is the most frequent time you guys are going to see this. Resulting disease can be vasculitis and nephritis because obviously it's affecting the blood vessels of the kidneys, so inflammation of the kidneys, as well as arthritis, if for any reason it causes inflammation in those joint here too. But it's due to those immune complex depositions because that's the whole point of that type three hypersensitivity. It's those antibody complexes building up in different points here. And this is in response specifically to types of drugs. But it is a form of rejection, you are rejecting a drug. And again, most frequently in IV, but as you can see from these other two examples here too, we can see rejection with a subcutaneous injection. We know this is known as the Arthas reaction and it'll just be perivascular, so blood vessels near the site of the subcutaneous injection. You'll start to see the redness and swelling and like the spots and the rashes coming off of that here too. And if you inhale it, if it's a reaction to an inhaled drug, we call this farmer's lung. I don't know where they got the term, obviously a farmer had to have been involved here too, but it's affecting the alveolar capillary interface in the lungs, but this is again a rejection of a drug. So even though technically I would classify this under drug reactions, it's technically considered a rejection and so we put it under transplant, even though technically we're not transplanting anything inside of the body. So that is just interesting to note overall here too. And so serum sickness by definition is an extreme form of type three hypersensitivity that can occur when therapeutic amounts of a foreign protein are injected. And so again, frequently seen, and that's I think the example Nate uses when he talks about this specifically, is like venom, an anti-venom that we'll use with snake bites. Wait, you guys do have snakes here. Nevermind, that was a very stupid question that I answered in my head. You guys have snakes in Indiana. I've seen one. I've seen one in the eco lab, you have snakes. I was gonna say it's more common. We do it a lot in Louisiana, because obviously people eat snakes, people catch snakes, it's kind of fun. If you don't know what kind of snake you're getting and it's poisonous, you should probably familiarize yourself with poisonous snakes of Indiana. But you will eventually have a small child. If you, say hypothetically, you go through BMS program and you're like, I hate this, I never wanna work with humans as long as I live. You go to vet school. There is also the risk that you could see this with animals too, because anti-venom is frequently used like dogs, dogs are gonna go after snakes. So if you decide to do vet school, that'll be relevant. Everything else, maybe not so much. So more effects that we can do too. We can also block cytokine signaling to prevent the activation of all alloreactive T cells. So especially if we know that that's coming and patients starting to reject, we can block cytokines. Overall, however, obviously, depending on which cytokines we block, do you think they're gonna be downstream effects? Yes, cytotoxic drugs do target the replication and proliferation of activated alloreactive T cells, which is one way we can also block those cytokine signals because T cells do secrete various cytokines as well. And then so this one is just showing you one specific example here, that in a low affinity IL-2 receptor, you're missing the other portions of it here, a drug that we have known as anti-CD25, it's an antibody to CD25, doesn't really recognize this receptor here and block it. But when you have a high affinity IL-2 receptor, you can actually use this drug called anti-CD25, it will bind on and it kind of blocks the space, preventing IL-2 from binding on, kind of giving that extra third signal we see with T cell activation when those cytokines are released to additionally provide effector functions and things like that too. And so I would, these are bolded here, these are more frequently used drugs, which is why I did include them. You need to know a couple of them just to be familiar with it here too. But the ones that are used clinically are chimeric basiliximab and humanize dacluzumab. You guys may have heard of those drugs before because they are used in other things besides transplantation here. What can you tell me about this name overall though? Like if you just saw this last word. It's a monoclonal antibody, so you guys are very smart. So say hypothetically, you go to residency and you're like, or a clinical rotation, they're like, hey, what does this drug do? Even if you don't really know what it does, you can be like, and you're like, mab, you're like, it's a monoclonal antibody. And then make an educated guess based on whatever case you're currently dealing with and what you think it might be. But you can at least be like, yes, that's a monoclonal antibody. And press all of your relatives, give me a drug name that you saw on TV recently, like monoclonal antibody, or ROC vaccine. That's the other one on TV right now. But besides that, you'd be fairly close in guessing monoclonal antibody. Unfortunately, this is a horrific fact. Patients needing a transplant outnumber the available organs in the United States. We also see this in the world too. So this red or pinkish color is the waiting list. The blue is the actual number of transplants and donors is in yellow. So it is very low overall here. And so patients who are eligible for a transplant usually have to wait about two to three years in the US, the UK before they receive a transplant. And so these have actually increased over time. One theory is this is due potentially to just increased lifespan. We are seeing patients live older, living to older lives. Therefore, if you get older, your increased risk of cancer, Alzheimer's, things like that go up. Also lifestyle choices, there's some discussion. For a while, my favorite fact was Louisiana had a billboard outside of our airport. Probably early 2000s. I said, Louisiana, number one in liver transplants. Because they were really proud of that until obviously all the tourists realized like, no, we're functioning alcoholics. That's why we're number one in liver transplants. Also, we have really high levels of hepatitis B spreading in Louisiana. And so it was not something to brag about. That billboard got taken down very quickly when they realized it was not. I mean, yeah, I'm like, heck yeah, if I'm gonna get a liver transplant, I'm gonna go to Louisiana. But also, no, no, maybe not. So unfortunately, that is an issue here too. Fun fact, they've done some studies to try to figure out what are ways that we can increase though. And one of the things that's like me encouraging you guys like all of us to just do the buckle swab, send them off, end up on the match registry. Again, your likelihood of being called is very slim. There still has to be matching. But increasing the numbers of people who might be available for testing to even see if you're eligible would be helpful here. But one interesting thing that they found, so when you go to the BMV, DMV, whatever it is, get your driver's license. And they ask you to opt in to being an organ donor. We have more times of rejection than in states and I'm sorry, countries where you are automatically opted in, you have to take extra steps to opt out. You're still allowed to, but they just automatically say you're an organ donor unless you go in and say, hey, I don't wanna be an organ donor. And so it seems like the general takeaway is that most people really just don't care. But if there's extra work involved in saying, nah, I don't want to, they're more likely to donate, which is interesting. But again, in the US, you have to go and tell them, yes, I would like to be an organ donor. And apparently that does decrease patient's willingness or like, I guess, DMV, BMV constituents. I won't call you guys patients if you're in the DMV, BMV, but preventing you from, it delays you like wanting to donate your organs overall. Plus horror stories about that. This is showing solid organ transplant activity across the world. And so we do see it frequently more so in first world countries. So a lot of Western Europe, US is a leader in transplantation. We have a lot of funding in there too. Probably also pharma, there's a lot of pharma money associated with that too. Canada as well. You really do not see any transplantation frequently in Africa, even in Eastern Asia or Western Asia, things like that. It is very slim. Who knows the reasoning behind that? Well, there's not enough trained physician in that field, not enough access, not enough repositories. I know B the Match is a United States organization, but they do work with other country organizations too, in case it ever works out. Canada, maybe there's someone in Toronto who was able to donate here too. That's just a fun fact overall. And so again, the need for HLA matching and immunosuppressive therapy does vary with the organ transplant here. If you are a squeamish round cadaveric eyes, you'll have to look at it eventually. But we do, I had a student my first year, he's like, I'm scared of eyeballs. And I'm like, you're going to be a doctor. You have to look at eyeballs at some point. Like, I don't know how else to dodge it. But anyway, this is a really cool, like, it's kind of sweet. I mean, it took me a while to get home. That's the thread that they stitched on corneal transplants, which is really cool. But who can tell me like thinking far back, what's unique about the eyes and the brain? What's the brain? There's nothing going on up there, right? There's no immune response in that. Like, we don't have, remember those selective areas, we frequently don't have an immune response. Because again, we don't get trained on all of the antigens present. And so eyes are one of the few where we actually really don't have to do, you know, super detailed matching with those. Because in a perfect world, there shouldn't have been any reason why your immune system should have, you know, gotten into your eyes and like, you know, developed immunity to your eyes. It shouldn't be in those areas. And so if we transplant a cornea, in theory, we shouldn't be seeing, you know, your immune cells are not going there. They're not gonna find the foreign antigen because they're not traveling to that area. And so we're slightly more likely to be able to do those. And so corneal transplants are actually one of the highest we do in the United States, just because they're easier because we don't have to do as much matching with that too. We also don't have to do as much immunosuppressive therapy. So it does vary depending on the location, you know, what type of tissue it is. If the immune is present, immune system is present in that area or not. So obviously like internal organs, yes, we have to do a lot more matching with that, but corneal surprisingly, and also we haven't done brain transplants yet. It's a slightly different discussion there. You still have an immune system in your brain. It's vastly different from the rest of your periphery though. So there is whole fields where you can just focus on the brain's immune system and neuroimmunology and transplantation overall, which is kind of cool. Also the amount of stitching, like, can you imagine like the number of glasses you would need to like just very carefully stitch an eyeball, like, whew, okay. So another fun fact that we can do too, hematopoietic cell transplantation is a therapy for both genetic and malignant diseases of hematopoietic stem cells. So things like cancer that we can do. And so all it's showing here is say you have a patient with cancer highlighted by like blue throughout their body, we can irradiate and give them chemotherapy where basically we are destroying all immune cells in their body, all cells were wiping out everything. They're considered severely immunocompromised at this point. They're in the ICU, but we can find a patient with similar cells and do a hematopoietic cell infusion here where this new bone marrow will replace the bone marrow and the cells throughout the new patient, thus making healthy. So this is not just in cancer too, certain genetic disorders too. Don't ask me for an example, but there are some where they know that if they wipe, like say it's just affecting your macrophages, we can go in and actually transplant out, you know, or like irradiate and destroy all the cells in your body pretty much, and then put in healthy bone marrow, replace your immune system from scratch. It is actually the way we've cured HIV. I say cure because it was 100% perfect. We've only done it in three patients and it was by accident. We irradiated them, we then did a bone marrow transplant, but their bone marrow transplant happened to have a CCR5 Delta 32 mutation, making them resistant to HIV. So when their bone marrow reseeded all the cells in this patient's body, the cells couldn't become infected by HIV and HIV died out in that host body because there were no cells that were capable of being infected anymore. So if you don't remember that fact, go back to the HIV lecture, I did talk about it, CCR5 Delta 32 mutation, you might see it on the exam. But that's a really fun fact that we were actually able to cure HIV through this accidental process. It was wild. They were trying to replicate it, but obviously you have to have a match of HLA who also have CCR5 Delta 32, which is not a lot of people, and so obviously that's why we haven't cured HIV for everybody yet here too. Oh, here's a list of all the different blood disorders you can do. We will talk about with Scott Aldrich, what we did already with some of the primary autoimmune, if you guys remember WASP here. We can also do it for osteopetrosis, ataxia, telangiectasia, so you guys remember some of these primary autoimmune disorders that we talked about. Sickle cell is also being used as a treatment for sickle cell disease as well. You don't have to memorize this, I just think it's a fun fact overall here too. But hematopoietic cell transplantation is a treatment for genetic diseases of blood cells here. We also use it for SID sometimes too, if it's possible. So pretty cool that we can treat overall. And so this is talking about how you do and the importance of why you need that matching. We've talked about the bad things, like obviously we don't wanna reject it because you need that matching, but again, I mentioned that good thing too. If your cells are speaking foreign languages with the donated tissue, they can't do their normal job either. So it is also important to have matching so that you can have a successful normal immune response against truly foreign things like bacteria, fungi, and parasites. And so this is the exact same picture twice with just two possible scenarios. And this first example here is a hypothetical transplant patient with a completely different HLA from his or her own. And the second one here is having some HLA class one and two in common here. And the takeaway, the dome-derived thymocytes are positively selected on recipient HLA allotypes. Those T cells are restricted by recipients, but not those donor HLA allotypes. So they're not going to interact with the host antigen presenting cells. If they can't talk to the antigen presenting cells that are really trying to like, they're like, hey, here's COVID, we have to do something, but they're speaking Finnish, it's not gonna work. And so it's especially important when we do hematopoietic stem cells that there is matching, particularly because again, if you have any antigen presenting cells left over and they're trying to do their job and present true foreign antigen of bacteria, viruses, fungi, those T cells that have been transplanted from that bone marrow won't interact, won't mount a response, you have no adaptive immune response, that patient will die from a secondary infection. Versus if we do have these matching, those cells have now been educated in the same language, they can talk to each other. And so you'll have those new T cells are able to respond to any leftover, dendritic cells, macrophages in the body that are saying, hey, here's the bad guy, here's COVID, we need to fight this. You are able to mount a successful adaptive immune response to clear the truly pathogenic infection. And so not just the risk of rejecting the host or the donated tissue, but also the cells need to be able to talk enough that they can continue to do their job well and mount a traditional immune response to as a big picture takeaway of both of those slides here too. You don't have to memorize this either, but allogeneic hematopoietic stem cell transplantation is the preferred treatment for many cancers, especially blood cancers, because again, it's replacing the stem cells where those cells came from. And after you wipe them out with the radiation and chemotherapy, you can replace them with healthy ones from a donor. It again is not a perfect system either. I know plenty of individuals who have passed away after multiple bone marrow attempts. So it still is unfortunate here too. And lastly, one of the main big risks that we'll talk about is graft versus host disease. I mentioned it very, very earlier on in last lecture. For the most part, we've been talking about how the host is rejecting the transplanted tissue. It's dangerous, not that risky. It's more dangerous when you have the transplanted tissue attacking the host and the new recipient of that tissue here, which is known as graft versus host disease here. And so the risk of this comes from if this transplant contains memory and mature T cells that are capable of functioning. We transplant them into the body, they go to secondary lymphoid tissues, like doing what they think they're supposed to do, they're just in a new location, they start telling all of the cells in the body, oh, because they're recognizing everything else in this new host body is foreign. They mount a wide scale attack on this new host. And it's like these T cell generals take over the host's army and just tell them to kill. And they will go through and just destroy the host. And so graft versus host is one of the most critical things we have to try to risk or avoid with transplants because it is a critical life threat here. And so those effective CD4 and CD8s will enter tissue, start killing the host, and it is awful. And once it starts, it is incredibly hard to stop because you have to go through and make sure that you have completely removed every single possible cell from the new host, very unlikely and very difficult to do, which is why we also have to immunosuppress the transplant donors first too, so that hopefully they don't have any mature cells capable of leading an army and then injecting them into this new unsuspecting host. And then their army just takes out everything here. I do expect you to know this, do not panic, pick one column and stick to that because I will provide multiple examples here because graft versus host is divided by these four different grades. One is the most mild, four is the most severe here. So I would say pick one and just go up by that one here. But how they measure it, skin if the rash is less than 25% of the body surface, it's considered grade one. If it's between 25 and 50, grade two, generalized erythroderma, which is all over the whole body, grade three. And if we start to see blistering and desquamation where basically you can't see lines on it, it's peeling and you're seeing patterns on the skin and it's all peeling off, that's grade four. Or you can go by serum bilirubin, you'll start to have increased bilirubin as the rejection progresses from two to three, three to six, six to 15 or 15 here. We also measure diarrhea because it will, the inflammation will cause massive gastrointestinal upset. I had a former student who worked in a transplant lab and especially with infants undergoing transplant, they literally measured how much they pooped every single day to see kind of if they were progressing to any of these levels of rejection and graft versus host disease overall. And then just last thing here, HLA matching of donor and recipient is most important for hematopoietic stem cell transplantation, that's the fact. It's just showing like the likelihood of survival of both survival and graft versus host disease with how much matching that we have overall. Don't panic about this one, I don't expect you to know any extra stuff with this one. Here, there are something known as minor histocompatibility antigens. Obviously they're minor, they're non- classical, they're very small components. We see them mostly with males as part of the Y chromosome. They're an extra factor that we have to look at with transplantations involving males. And so that's the fact that I expect you to know from this slide here, it's providing some examples here. Oh, there's more slides. Okay, well, we'll just pick up next class. I figured we were at the end. Sorry, transplantation is long because there's a lot of stuff to cover in it. And it's like one of the most, as you can see from the US's number one in transplantations, it's actually a very, very lucrative field overall. And so, I got something you're interested in. I can give you some names. Actually one of the second years that you guys talk to frequently works for a transplant lab at Riley. If you're interested, let me know and I'll connect you guys.