Antigens - Leukocytes - Immune Cells - Lecture 2 PDF

ANTIGENS - LEUKOCYTES - IMMUNE CELLS - lecture 2 Monday, October 2, 2023 12:24 PM ANTIGENS AND ANTIBODIES THE BLOOD: LEUKOCYTES → Blood types depend on surface antigens on er...

ANTIGENS - LEUKOCYTES - IMMUNE CELLS - lecture 2 Monday, October 2, 2023 12:24 PM ANTIGENS AND ANTIBODIES THE BLOOD: LEUKOCYTES → Blood types depend on surface antigens on erythrocytes → White blood cells (WBCs) - in the blood ○ Antigens = large, complex molecule that triggers a specific immune response against itself when it gains entry to → Mobile units of body's immune system the body → Are made up leukocytes, their derivatives, and variety of plasma proteins and immune organs ○ Antigens are found in the surface of RBC, stick out to identify RBC ○ Immune cells have different shapes and functions ○ 100 types on RBC ○ Immune cells can produce defending substances, can communicate to call reinforcements ○ Most antigens are proteins → Plasma proteins are involved in the immune system → Immune cells did not evolve on purpose to fight transplants ○ Compliment protein is made by the liver but has immune functions ○ Ex: immune system will destroy an organ that isn't the proper blood type ○ Globulins is made by immune cells ○ Ex. The antigen on cancer cells are not liked by the immune system so it reacts and attacks it ○ Immune cells use receptors as eyes to see / identify antigens → How pathogens enter the body: → Lymphocytes recognize antigens and produce antibodies against them ○ Don't go straight to the blood vessels but are in the tissue ○ Antibodies = bind with the specific antigen against which it is produced and leads to the antigen's destruction ○ Enter through holes in the body, little cuts etc by various means ○ Can be found on food and in the air (respiratory viruses) ○ Immune system have learned to tolerate our own antigen § React to foreign antigens ( not always ) → Analogy for immune system: § Foods have antigens -> allergic reactions ○ A country (body) defending itself from an enemy (pathogen) § There are different reactions to pathogens § The country defends itself with military units or forces (immune system has different units) ○ Lymphocytes produce antibodies § Ex: covid -19: vaccines contain antigens of covid and our body will recognize it create antibodies for it so HOW LEUKOCYTES WORK (vaguely) when it's present a second time our body will know how to react to it ○ Antibodies bind with specific antigen → (1) the immune system recognizes and destroys or neutralizes materials within the body that are foreign to "normal ○ Pathogens change that's why some viruses can hit a second time self " ○ Uses receptors to identify threat BLOOD TYPES → (2) defends against invading disease-producing microbes (e.g. bacteria & viruses) → (3) functions as a "cleanup crew" -> removes worn-out cells (e.g. aged RBCs) & tissue debris (e.g. ones damaged by → ABO Blood Types (most common blood antigen system) trauma or disease) -> wound healing & tissue repair ○ Decoration to RBC, does not trigger immune system ○ Cells and tissues die and the damaged site needs repairing → Main concept: identifies and destroys cancer cell that arise in the body → "seek out and attack" strategy → Naturally occurring antibodies: against foreign RBC antigens → Always a life or death situation Called "a" b/c it was Appear in human plasma after 6 months of age first in the alphabet ○ Occur naturally b/c year not getting exposed to the antigen TYPES OF LEUKOCYTES → Colourless: lack hemoglobin (stained for visualization by microscopy) → Vary in structure, function, & number (unlike uniform RBCs; size > RBCs) → Five major different types of circulating leukocytes 1. Neutrophils - most abundant immune cell in the blood 2. Eosinophils → Transfusion reaction: e.g. a transfusion reaction resulting from type b blood being transfused into a recipient with type 3. Basophils - least abundant immune cell A blood 4. Monocytes ○ Occurs in the blood vessels 5. Lymphocytes Picture description: → There are other important immune cells that don't primarily circulate in the blood → When the different blood types mix, the antibodies POLYMORPHONUCLEAR GRANULOCYTES: NEUTROPHILS on A will bind to antigen B → The antibodies will cause the RBCs too rupture and → polymorphonuclear (PMNs) - many-shaped nucleus - still one nucleus jus multi shaped be destroyed → Granulocytes - granule-containing cells → This is bad bc it will cause a blockage in the blood vessel → Neutrophils ○ Has granule but pH = neutral Additional notes ○ Granule is acidic so it binds to acidic molecules/ granules § Is stained in red → Blood will aggregate and clot if incorrect blood ○ Blue dye is basic types are crossed ○ Phagocytic specialists -> eat pathogens → Clumps can be seen w the naked eye ○ Engulf and destroy bacteria intracellularly → Rhesus (Rh) Blood group: § As soon as a pathogen is detected in the tissue, the neutrophils ○ CDE system; 50 blood-group antigens with 5 primary antigen group (D, C, E, c, e…) -> fisher-race system enter in a large number FIRST, and most die due to being the first defense ○ D = positive ○ Release web of extracellular fibers called neutrophil extracellular traps (NETs) that ○ No D = negative contain bacteria-killing chemical § No lowercase D § Sticky substance to trap the pathogen ○ Ex: someone with the C antigen will NOT have the c one. Same pattern follows for the other antigen - remember ○ Are very selfless - first defenders agonist bacteria there are two alleles § Only one allele needs D to be positive since D is dominant POLYMORPHONUCLEAR GRANULOCYTES : EOSINOPHILS ○ There is no d antigen; sometimes 'd' is used to denote the absence of the D antigen ○ The D antigen is commonly found in the population and is the most abundant and most antigenic -> most → Eosinophils important → Acidic granules (red dye) ○ The older terms Rh factors, Rh positive (Rh+) or Rh negative (Rh-), refer to the D antigen → Its job is to fight and kill parasite / parasitic infections and capture and release granules to kill ○ Ppl who have the Rh factor have Rh-positive blood (D) → Killing of antibody coated parasites through release of granule contents ○ Ppl lacking the Rh factor are Rh-negative (d) → Increase in circulating eosinophils (eosinophilia) is associated with: ○ No naturally occurring antibodies develop against the Rh factor ○ Allergic conditions such as asthma and hay fever § This means, you need to be exposed to it to make antibodies for it § Come from the eosinophils degranulating on innocuous things □ + and + is fine ○ Internal parasite infestations, such as worms □ + and - is still fine bc there's no antigens on the - so there won't be antibodies against it § Attach to worm and secrete substances to kill it ○ Anti-Rh antibodies are produced only by Rh-negative ppl is exposed to Rh-positive blood (after blood transfusion → They don't know when to kill but have learned to identify special type of antibodies that can only coat parasites or placental exposure during pregnancy) ○ The body will coat things that think are parasites TEXTBOOK NOTES: → anti-Rh antibodies are produced only by Rh- individuals, and if exposed to foreign Rh antigens like Rh+ they become POLYMORPHONUCLEAR GRANULOCYTES : BASOPHILS sensitized to Rh+ antigens → Rh+ individuals never produce antibodies against the Rh- factor that they themselves possess, therefore Rh- ppl should → Basophils = bind to basic dyes - dye is blue only be given Rh- blood → Chemotactic factor production → Rh+ ppl can safely receive either Rh- or R+ blood → Least numerous and most poorly understood of the leukocytes ( controlling immune responses to parasites ) → Synthesize and store ○ Histamine: release is important in allergic reactions ○ Heparin: speeds up removal of fat particles from blood after fatty meal § Prevents coagulation (clotting) of the blood MONONUCLEAR AGRANULOCYTES : MONOCYTES → Means it’s a single nucleus (simple shaped) and cells lack granules → Monocytes - larger, can eat more ○ major function: Phagocytosis, antigen presentation cytokine production and cytotoxicity ○ Emerge from bone marrow still immature; circulate for 1-2 days; settle down in various tissue ○ Matures and enlarge in resident tissue -> become macrophages § Life span can range from months to years □ Dies sooner while performing phagocytosis □ Can ingest only a limited amount of foreign material before it succumbs ○ Communicates: make proteins called cytokines and chemokines ( the subgroup of cytokines that only attract other cells) ○ Tissue resident Macrophages first to sense invading microorganisms -> secrete cytokines/ chemokines -> recruit neutrophils and other leukocytes § They eat dead neutrophils MONONULCEAR AGRANULOCYTES : LYMPHOCYTES 1. Large granular lymphocytes ( HAS GRANULES ) aka natural killer (NK) cells → Effector cells of the innate immune response → Extremely effective against virally infected cells → Release lytic granules to kill infected cells → Produce cytokines to limit viral replication → Cells show that they're healthy or infected ( like an ID) ○ This function was learned / evolved → NK cells will attack the infected cells → Even with viruses evolving to hide the ID from cell the NK cells will kill it anyway bc it was called to the site meaning something is still wrong 2. Small lymphocytes of adaptive immune response → Cytokine production, antigen recognition, antibody production, memory, cytotoxicity → Two types of lymphocytes: → B lymphocytes : humoral immunity ○ Produce antibodies ( as a plasma cell ) ○ Responsible to antibody-mediated immunity □ Turns into plasma cell when fully differentiate and filled with ER that makes protein which will make antibodies → T lymphocytes : cell-mediated immunity ○ Do not produce antibodies ○ Directly destroy specific target cells by releasing chemicals that punch holes in the victim's cell □ Chemical is called cell-mediated immunity ○ Target cells include body cells invaded by viruses and cancer cells ○ Act as NK cells ○ Command, act like the general of the military, tells B cells where to go and have a plan of attack LEUCOCYTE PRODUCTION → All blood cells ultimately originate from same undifferentiated pluripotent hematopoietic stem cells in red bone marrow → Granulocytes and monocytes are produced only in bone marrow → Most new lymphocytes are actually produced (via cell division) by lymphocytes already in lymphoid tissues such as lymph nodes, spleen and tonsils → Total number of white cells and percentage of each type may vary considerably to meet changing defense needs