MTAP-1 Immunology and Serology (Discussion of Prof. Balce) PDF

MTAP-1 Immunology and Serology (Discussion of Prof. Balce) Note: I. Introduction to Immunology He discovered that individ...

MTAP-1 Immunology and Serology (Discussion of Prof. Balce) Note: I. Introduction to Immunology He discovered that individuals exposed to a less-pathogenic agent related to smallpox did not develop small pox - which is Cowpox = Vaccinia virus - Immunology where vaccine / vaccination term was first used. Study of the molecules, cells, organs, and systems responsible for the Jenner used 1 organism to mount an immune response recognition and disposal of foreign or non-self material against another organism, it is called cross immunity ○ Primarily molecules and cells. or cross reactivity - when 1 agent evokes an immune ○ “Immune Response” - an interplay between humoral factors (molecules) response against 1 agent and another related agent. and immune cells (cells) which are found in specific organs / systems of the body. This approach was not perfected. The one that has How immune system components respond and interact perfected vaccination technique was Louis Pasteur with The desirable and undesirable consequences of immune interactions the discovery of “Attenuation”. ○ Immunity - Desirable consequence of immune interaction (protection). ○ Immune Disorders - Undesirable consequence (either lack of certain Vaccine Attenuation components or exaggerated response like hypersensitivity, autoimmunity chicken cholera, anthrax, and rabies vaccines etc.). The ways in which the immune system can be advantageously manipulated to Note: protect against or treat disease. Attenuation - Weakening the virulence while keeping ○ Through vaccinations, immunotherapy, transplantation etc. the immunogenicity intact. It is when organism is weakened so that it won’t produce disease but is strong enough to mount an Louis Pasteur (Father of 3 immune response Immunology) Immunity (Late 1800’s) Virulence - Development of signs and symptoms of The ability to resist damage from foreign substances such as microorganisms, disease (because of virulence factors) ; ability to cause toxins, and altered self-molecules or cells. disease or evade host’s responses. Note: Immunogenicity - Ability to mount or evoke immune There are cells that belong to “self”, but when altered, they also become foreign to the body. response. This is the case in “tumorigenesis” or cancerogenesis” - where nagbabago ang cells - ang nag pproduce ng molecules ang cells na hindi pinoproduce ng normal cells - as a result, nagrereact ang immune system - hence hindi lang bacteria and other pathogens ang foreign Phagocytosis bodies. Cellular Theory of Immunity Note: He worked on starfish larvae, injected it with a Elie Metchnikoff 4 foreign body and observed “amoeboid body” - he (Late 1800’s) Discovery/Contribution Pioneering Scientist/s referred to those amoeboid cells as phagocytes. She attributed immunity to cells - (Cellular Theory of Variolation Immunity). inhalation of dry scab powder from Smallpox 1 N/A (“Variola virus”) lesions practiced by the Chinese around 1000 AD Smallpox Vaccination Edward Jenner 2 Phenomenon of cross - immunity (1798) 1 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) Group of proteins / humoral components that (1894) Diphtheria Antitoxins complements antibody response Humoral Theory of Immunity Emil von Behring 5 Side Chain Theory (Late 1800’s) Note: He said that immunity is due to humoral components. Note: It is a simplistic attempt to explain how antibodies are produced. He said that cells contain side chains, and when they interact with specific antigen they would Opsonins Almroth Wright break off from the surface of cells and become Paul Ehrlich 13 “Correlated phagocytosis antibodies. (1900s) Note: During 1903, He linked the two theorists - (Elie the 6 and diphtheria antitoxin Cellularist and Emil the Humorist). He said that immunity debate” This was already disproved, because there is a degree is an interaction between cellular and humoral (1903) of specificity or complementarity- the lock and key factors. specificity between antigen (epitope) and antibody receptor. Immunologic tolerance Non-reactivity to self-molecules or cells Clonal Selection Theory The antigen binds a cell bearing specific Note: Question answered: Frank Macfarlane (F.M.) receptor it will go through mitosis Why do our immune cells not respond to the antigens 7 Burnet and Peter Medawar found in our body? Immune cells are taught not to Niels Jerne and Frank (1953) Note: When antigens gain access to the body, they seek tolerate or to not react to anything that belongs to 14 MacFarlane (F.M.) Burnet out the specific cells bearing the specific receptor. self (Immunologic tolerance), because reaction to (1957) Once the ag binds to it, the cell undergoes clonal anything that belongs to self is “Autoimmunity” or expansion (division/mitosis) giving rise to clones of cells failure of immunologic tolerance. giving the same specificity, hence the body will produce antibodies with the same specificity. Paul Portier and Charles Immediate hypersensitivity 8 Richet Type 1 hypersensitivity Two-Gene Model of Antibody Synthesis (1902) William Dreyer and Jean Note: This model claims that immunoglobulins are coded Robert Koch 15 Claude Bennett 9 Delayed Type Hypersensitivity for only by two genes (which is wrong) because it is (1891) (1965) coded for by several gene segments - thanks to Somatic Recombination Theory of Susumu Tonegawa. Human Blood Groups (1901) and Haptens (1917) Somatic Recombination of Immunoglobulin Genes He wrote a book entitled “Specificity of Serologic 10 Karl Landsteiner Note: Her discovery was a breakthrough because Reactions” - which is all about the activity of “Haptens” Scientists were puzzled as to how it is possible to - which exhibit a certain degree of specificity to receptors produce millions of antibody specificities when we - because a hapten represents an epitope- which binds only have a limited number of genes (because the to a specific receptor. Susumu Tonegawa 16 common knowledge is 1 gene = 1 protein) and because (1978) antibodies are proteins, others claim that there are George Snell, Jean millions of antibody specificities, that would mean, they Major Histocompatibility Complex Dausset and Baruj are coded for by millions of genes (where we only have 11 (MHC) or Bernacerraf approximately 25 thousand genes in the human body - Human Leukocyte Antigens (HLA) (1972) which is limited). 12 Complement Jules Bordet 2 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) Susumu Tonegawa claimed that there are specific gene II. The Immune System segments, and these segments undergo recombination (analogy is like Lottery - konti lang numbers na tatayaan pero pag pinag combine mo sila, millions ang lalabas na combinations). She explained that immunoglobulin molecules are coded for by gene segments that recombine in a specific fashion producing millions of combinations - which disproved the two (2) gene model. Gerald Edelman and 17 Basic Immunoglobulin Structure Rodney Porter (1959 - 1962) Radioimmunoassay (RIA) Note: This is the first labeled immunoassay Rosalyn Yalow 18 developed. Not popular today because of the hazard (1959) associated with radioactive materials that are used as labels. During these times, they use “polyclonal” antibodies (Ab with many specificities or non-specific). Discussion: All blood cells arise from Pluripotent Hematopoietic Stem Cells which give Monoclonal Antibody (mAb) Production rise to two progenitor cells: Note: Uses hybridoma technology. “Monoclonal” Common Myeloid Progenitor Cell (CMP) Common Lymphoid Progenitor Cell (CLP) 19 means cells have the same specificity which produces (1975) (Innate Immunity) (Adaptive Immunity) the same antibody with the same class, same idiotype produced by 1 clone of cells - and therefore more specific and not subject to cross reactions. Gives rise to: Gives rise to: 1. RBC 1. T - lymphocytes - Adaptive Immune 2. PLT Response; differentiates into different Luc Montagnier and 3. Granulocytes effector T-cells: 20 Human Immunodeficiency Virus (HIV) Francois Barre-Sinoussi 4. Monocytes (not terminally differentiated a. Helper cells (1983) because it gives rise to macrophages) b. Regulatory cells and; c. Cytotoxic cells Tak Mak and Mark Davis 21 T-Cell receptor (TCR) 5. Dendritic cells (could be derived from 2. B - lymphocytes - Adaptive Immune (1984) CMP, Monocytes, and/or CLP - but still Response; differentiates into: are grouped in the innate immune a. Plasma cells - produces response. antibodies a. On the other hand, NK cells b. Memory B-cells arise from CLP but form part of 3. NK Cells - Innate Immune Response the innate immune system as well). 3 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) Mast Cells Tissues Larger and more granules A. Myeloid Cells same granule contents as basophils: Histamine Cell Type Localizati Function/s Other Comments Heparin on Eosinophil Chemotactic Factor A (ECF-A) Granulocytes plus enzymes: they respond to antigen by releasing granule components ACP ALP Proteases Neutrophils Blood Phagocytosis, Respond to chemotaxins; (1,800-7,8 inflammatory granules contain: 00/µL) response Myeloperoxidase (MPO) Agranulocytes or “Mononuclear Phagocyte System” Fastest response Elastase (They all act as antigen-processing/presenting cells (APC)- they process antigens and to chemotaxis Lysozymes present it to the components of the adaptive immune response or the lymphocytes). Inflammatory Lactoferrin response NADPH oxidase Monocytes Blood Phagocytosis and Respond to chemotaxins; Not (0-900/µL) Antigen presentation terminally differentiated because Eosinophils Blood Killing of Some phagocytic ability; they migrate to tissues and gives (0-150/µL) antibody-coated regulate inflammatory response rise to macrophages parasites through through neutralization of basophil / releasing granule mast cell products via release of contents granule components: Major Basic Proitein Macrophages Tissues Phagocytosis; Types: (MBP) elimination of bacteria, 1. CT - Histiocyte Cationic proteins intracellular parasites, 2. Brain - Microglia Peroxidase tumor cells; secretion of 3. Lungs - Alveolar Eosinophil-derived cell mediators; antigen 4. Liver - Kupffer cells Neurotoxins presentation 5. Spleen - Splenic 6. Lymph Nodes- Sinus / Basophils Blood Type 1 Hypersensitivity Induce & maintain allergic Subcapsular (0-200/µL) reaction - by releasing reaction (histamine production) 7. Peritoneal cavity - Serosal granule components and stimulates production of IgE. Macrophages 8. Kidney - Renal/ Mesangial The only WBC with IgE receptor 9. Bone - Osteoblast Note: Basophils and 10. Synovial - Type A cells Mast cells degranulate Granules contain: when an allergen binds Histamine Dendritic Tissues Antigen capture, Types: to IgE antibodies on their Heparin Cells processing, and 1. Skin - Langerhans cells surface, triggering a Eosinophil Chemotactic presentation to helper T 2. Lymph Node Paracortex - release of inflammatory Factor A (ECF-A) cells in the blood and Interdigitating Dendritic mediators like histamine. lymphoid organs Cells 3. Lymphoid Follicles This release causes Most potent/efficient (Spleen and Lymph symptoms of allergic APC -easily capture Nodes) - Follicular reactions, such as antigen Dendritic Cells swelling and itching. 4 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) 4. Major Organs - Interstitial 3. Mucosa-Associated Lymphoid Tissues (MALT)- include Dendritic cells the: Gut - GALT Bronchus- BALT B. Lymphoid Organs (where lymphoid cells are produced and undergo maturation) Nasal - NALT Skin - SALT, and Other lymphatic aggregates 1. Bone marrow Source of B and T cell precursors Primary / Central ○ T cells leave the bone marrow and migrate to Antigen independent thymus for maturation. lymphopoiesis ○ Site of B cell maturation (maturation) takes place 2. Thymus site of T cell maturation and education Note: Antigen-independent lymphopoiesis means that maturation is spontaneous in the Primary / Central lymphoid organ. 1. Lymph nodes Major antigen-trapping sites of the body Distributed in the body Paracortex contains T-cells (T-cell zone) Follicles / Germinal centers contain B-cells ○ Follicles contains naive B cells Lymph Node ○ Germinal centers contains activated B cells) The germinal center of a lymph node is the site where B cells become activated, proliferate, and differentiate in response Secondary / Peripheral to an antigen. Antigen dependent lymphopoiesis Within the germinal center of a lymph node: (differentiation) takes A. Activation occurs when B cells encounter an antigen. place B. In the dark center (or dark zone), activated B cells rapidly proliferate and undergo somatic hypermutation to create a variety of antibody affinities. C. These B cells then differentiate into plasma cells, which produce antibodies, or memory B cells, which provide long-term immunity. 2. Spleen Largest secondary lymphoid organ If dark areas exist in the middle part of the follicle that are rapidly dividing, those are Consists of red and white pulp considered as the germinal center, and the primary follicle is now called the secondary Periarteriolar Lymphoid Sheaths (PALS)- contain T follicle. cells; counterpart of Paracortex of Lymph Nodes. Follicles / Germinal centers contain naive and activated B cells 5 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) TCR (T Cell Receptor) BCRs (B Cell Detects processed Receptor) Spleen antigens only Surface IgM and Consists of αβ (alpha Surface IgD beta) or γδ (gamma (both must be delta) chains surface-bound) Most population are αβ (alpha beta) No Antigen Receptors (only surface markers: CD16 and CD56) Antigen receptor Note: Note: Its response is non- Both IgM and IgD must specific because they Periarterial lymphoid sheath (PALS) - an important part also known as T cells zone that is be bound in the surface have no Ag receptor. a region surrounding the artery branches. Lymphoid sheath because it is composed of (because there are IgM sheaths of lymphoid cells. and IgD molecules that T cells - lymphoid cells on the lymphoid sheath. Note: are free in plasma). Note: Secondary follicles means that the T cells are already activated. TCR Requirement- an antigen must have been For a B-cell to be processed by an APC mature and ready to be (antigen presenting cells) for activated (to populate C. Characteristics of Lymphoid Cells it to be detected by TCR. the secondary lymphoid organs), it must bear both presenters - T cells B cells NK cells dapat expressed na (Adaptive; specific (Adaptive; specific (Innate; non-specific both ng IgM and IgD response) response) response) on the surface, hindi pwedeng isa lang. —-Clusters of Differentiation— Relative number (% of total 60% - 80% 10% - 20% < 20% lymphoid cells) Antibody Dependent Primary Cell-Mediated Immune Humoral Immune Cell-mediated function Response (CMI) Response (HI) Cytolysis (ADCC) Granzymes, Perforin, Cytokines (which Products Cytokines Antibodies destroys the target cell: tumor cell or virally infected cell) 6 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) 1. CD19 T Cell and B Cell Communication: Class Switching Also known as 1. CD2 - Sheep RBC / pan - B marker SRBC A cell that does Receptor in not have CD19 Rosette assay is not a B cell. T Cells that will form rosettes with 2. CD20 SRBC are counted Calcium as T cells. channel 2. CD3 - TCR associated 3. CD21 signal transduction 1. CD16 Receptor for molecule (found in all T Acts as an FC Epstein-Barr cells) receptor for the virus and Also known as FC portion of an complement pan- T marker antibody (CR2) (Marker of ALL molecule - which Other surface T-cells) serves as an The CD40-Ligand in a T-cell interacts with CD40 in a B-cell (and somewhat telling B-cell to markers 4. CD40 A cell that does not opsonin only. undergo class switching: from IgM to IgG/ IgA / IgE but with the same specificity). From Facilitates T cell have CD3 is not a and B cell IgM to: T cell. 2. CD56 communication Regulatory If there is a need for secondary response - IgG / interaction If antigen is inhaled or ingested - IgA 3. CD4 - T helper cells molecule HIV receptor If antigen is an allergen - IgE 5. MHC II important in 4. CD8 - T cytotoxic cells antigen Either CD4 or CD8, presentation Differentiation Phases: T-Cell and B-Cell but can’t have both. Note: We also consider 5. CD40 Ligand (CD40L) B cells as Antigen Facilitates T cell- B A. T-Cell Maturation and Differentiation Presenting Cells. B cell communication cells can respond to / interaction and process Binds to CD40 on B uncomplicated or 1. Antigen - Independent Phase ; Maruration (Thymus) cells simple antigens Outer cortex This is where you will find the Double Negative (DN) Thymocytes Mitogens ○ CD4 Negative ; CD8 Negative Pokeweed Mitogen Pokeweed Mitogen Substances that This is where the T-Cell Receptor (TCR) gene is expressed and Phytohaemagglutinin Protein A (Staph) N/A stimulates synthesized. Concanavalin C LPS (Gram -ve) mitosis Inner cortex This is where you will find the Double Positive (DP) Thymocytes ○ CD4 Positive ; CD8 Positive Acquisition of CD2 and CD3 (in addition to CD4 and CD8) Full expression of TCR Medulla This is where you will find the Single Positive (SP) Thymocytes ○ Either CD4 Positive OR CD8 Positive (never both) ○ One of CD4 or CD8 will be down-regulated 7 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) Note: that do not bear functional TCRs will die / destroyed (by dendritic cells - yung may When we use the terms DN, DP, SP, we are only referring to CD4 and CD8 (but there starlike image sa diagram). Yung magssurvive (because may functional TCR sila) will are other CDs / Surface markers on the surface of T-Cells). be subjected to further selection process which is called “Negative Selection” - which In the Medulla - the production is either CD4 and CD8 only - they will now migrate to means destruction of self-reactive cells. At this point, cells will be tested against self the peripheral tissues and will await for stimulation and activation (which is now the molecules. It will be determined if they are tolerant to self molecules or not. If they are Antigen Dependent Phase) not tolerant (or they react to self-cells), they must be destroyed or will not be allowed to leave the thymus. 2. Antigen - Dependent Phase ; Differentiation (Periphery) Lastly, one of the two markers (CD4 or CD8) will be downregulated and will leave the Gives rise to Effector and Memory T-cells thymus with functional TCR and will not attack self-molecules. Mature T-cells that are Happens in the secondary lymphoid organs released from the thymus will now populate the “Secondary Lymphoid Organs” - Spleen, Lymph Nodes and MALT to undergo differentiation following activation of specific antigen. Once they are activated, they give rise to “T-cell Subsets” or “Effector T-cells” B. T-Cell Subsets or “Effector” T-Cells T- Helper CD4+ Cells 55-70 % of peripheral T cells Recognize antigen in association with MHC Class II molecule Th0 Cells Differentiate into Th1 or Th2 cells 1. T-Helper Cells Aka “Naive T-cells” Th1 Cells Initiate delayed-type hypersensitivity reactions and help in the development of CD8+ T Cells Important in immunity to intracellular pathogens Secretes: Th1 Cytokine Profile: IL2, IFN-Gamma and TNF Th2 Cells Nature of Ag is extracellular Note: In the illustration, there are Cortical (Cortex) and Medullary (Medulla) regions. Stimulate B cell division and differentiation Review: The T-cell precursors (and all precursors) come from bone marrow and migrate to Secretes: Th2 Cytokine Profile: IL4,5,6,10,13 the Thymus for maturation. 2. T-Cytotoxic Cells CD8+ In the Thymus: Recognize antigen in association with MHC class I molecule In DN Phase: Si T-cell precursor (TP) ay wala pang markers na expressed (because it Destroy target cells through release of granzymes, perforins and cytokines (same components released by NK cells) is in Double Negative phase). During DN phase, TCR gene synthesis will begin and will give rise to cells bearing TCR. 3. T -Suppressor CD8+ cells Inhibit antibody production and T helper cell function In DP phase, complete expression of TCR happens in conjunction with its co-receptor, CD3 (which is the signal transduction molecule). It is in this stage where CD2 and 4. T regs or CD4+ and CD25+ CD3 is acquired kasi CD3 is needed for the full expression of TCR gene. It is also in Regulatory cells Inhibit immune response to self this stage where there CD4 and CD8 and both positive. Once TCR is already fully expressed, the cells will now be subjected to “Positive Selection” - which means survival of cells with functional TCR - meaning, cells 8 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) Start of somatic recombination Immunoglobulins or antibodies Pro-B ○ Consists of heavy and light chains Heavy chain gene are the first one to undergo rearrangement Pre-B Light chain gene rearrangement Immature B Heavy and light chains = Immunoglobulin M (IgM) Both IgM and IgD Ready to be released in the secondary lymphoid organ Note: When a cell already has a complete set of receptors namely surface Mature B Remember: IgM and IgD = it is now considered a Mature B cell and is ready to be T cells recognize Ag via T-cell receptor (that they have on their surface) and Ag is presented released. The differentiation of Mature B cells leaves Plasma or Memory B from an APC (as shown in the image) - which could be a Monocyte, Macrophage or Cells. Dendritic Cell Next step is Antigen presentation to Th0 or Naive T-cell (fresh from thymus). Once there is antigenic stimulus from APC, Th0 or Naive T-cell differentiate to Th1 or Th2 The receptor if found in the surface cells With only one surface immunoglobulin: either IgG, IgA, or IgE Memory B (depends on the nature of the antigenic stimulus) Functions as an immuno-surveilance (anamnestic response) Life span: 20 years or longer Secretes antibodies Plasma Cell Not expressed on the surface Well defined rough endoplasmic reticulum Note: Maturation Phase in Bone Marrow (Primary Lymphoid Organ); Ag Independent Pro-B Pre-B Remember: Immature B The Ag is being presented in association with MHC Class I to the TCR of T-Cytotoxic Cells, Mature B (sa primary lymphoid organ kasi sya nabubuo kaya kasali parin sya) then it is being stimulated to release its contents: ganzymes, perforin and cytokines. Differentiation Phase in Peripheral Tissues (Secondary Lymphoid Organ); Ag dependent Perforin is a protein that “perforates” or creates holes in cell membrane and will result to Mature B lysis of cell, hence cytotoxic cells (destroys target cells= tumor cells or virally infected cells). Memory B or; Plasma Cell C. B-Cell Maturation and Differentiation Non-T, Non-B Lymphocytes (No CD3 = Non T cell / No CD19 = Non B cell) No surface markers found in T cells and B cells instead they Natural Killer only have CD16 and CD56 Cells (NK Cells) Large granular lymphocytes that lack CD3, CD4, CD8, CD19, and lymphocyte antigen receptors Not MHC restricted (Innate / non-specific)- so their response to target cells is much faster and more efficient compared to T-cytotoxic cell 9 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) First line of defense against target cells (virally infected and Note:All of 1st line of defense are tumor cells lacking MHC class 1) here Destroy antibody coated target cells by releasing perforin, granzymes, and cytokines - IFNƔ and TNF Memory No Yes (aka anamnestic response) Lymphokine Activated form of NK cells that have been stimulated in vitro by Cellular Granulocytes, Mononuclear T and B cells Activated Killer lymphokines (IL2 or IFNƔ) Components Phagocyte System (MPS), NK Cells (LAK) Kill tumor cells more effectively than NK cells Used in immunotherapy - to regulate the activities of the immune system; cure cancers. Humoral Non-specific proteins Antibodies Components (produced by B cells) B. INNATE IMMUNITY 1. Anatomic and Physiologic Barriers (1st line of defense) 1. Lysozyme in tears and nasal secretions 2. Intact skin and mucous membranes 3. Coughing, sneezing, vomiting, flushing action of urine and tears 4. Secretions from gland of the skin 5. Ciliated cells lining the respiratory tract (when the Ag is inhaled) 6. Commensal organisms and secretions of organs (Normal flora or Normal Microbiota - protect us from pathogens by displacing them via “competitive” exclusions - they compete with pathogens for sites, nutrients etc. 7. Gastric acid and vaginal lactic acid 8. Acid pH of stomach III. IMMUNITY 2.Inflammation A. BRANCHES OF THE IMMUNE SYSTEM A. Stages a. Vascular Response – vasodilation, increased capillary permeability, exudate formation INNATE (Natural) ADAPTIVE (Acquired) b. Cellular Response – phagocytosis c. Appearance of Classic signs: Receptors Germline-encoded Undergo Somatic Mutation i. Dolor (pain) ii. Calor (heat) Note: Germline - kung ano Note: Somatic mutation improves iii. Rubor (redness) yung encoded sa cells, yun lang affinity. This is associated with the yung ma-eexpress nila kasi phenomenon of class switching. iv. Tumor (swelling) non-specific sila. There’s affinity maturation. v. Function laesa (temporary loss of fx) d. Resolution and Repair Specificity Non-Specific Specific B. Mediators of Inflammation a. Preformed Molecules – histamine, serotonin, lysosomal proteins Response Immediate (0-6 hrs.) Slow (3-5 days) b. Newly Synthesized – prostaglandins, leukotrienes, PAF, reactive oxygen species, Time NO, cytokines 10 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) 3. Phagocytosis (I.C.E.D) 1. INITIATION – phagocyte interaction with the vascular endothelium through CAMS (Cell Adhesion Molecules) ○ Selectins - mediate rolling of neutrophils ○ Integrins - facilitate firm transient adhesion prior to transmigration ○ Diapedesis - squeezing between junctions in the endothelial wall of blood vessels 2. CHEMOTAXIS – migration of leukocytes primarily neutrophils to the site of injury ○ Chemotaxins/Chemokines: C5a, IL8, Leukotriene B4 3. ENGULFMENT ○ Also called “Invagination” ○ In order to enclose the foreign body forming a phagosome is important ○ Binding and recognition are necessary steps prior to engulfment ○ Opsonization makes the binding and recognition possible ○ Opsonins substance that coats microbial particles to improve the efficiency of engulfment ○ Opsonins includes: IgG (most coatable) and C3b 4. DIGESTION ○ 2 types of digestion Oxygen independent - Fusion and degranulation - process by which cytoplasmic granules Note: HClO - Hypochlorite/ Hypochlorous acid (bactericidal agent). This is the natural fuse with and empty their contents into the phagosomes. hypochlorite inside the phagocytes that generates the following oxidative burst. (ex. granules of neutrophils will have fusion in phagosome) Oxygen dependent - Oxidative burst/ Respiratory burst/ Metabolic burst - generation of bactericidal agents in the presence of myeloperoxidase, NADPH 4. PPRRs (Primitive Pattern Recognition Receptors) oxidase, and superoxide dismutase - More efficient and effective way to destroy pathogens. - Expressed by neutrophils, monocytes, macrophages. - Recognizes PAMPs (pathogen associated molecular patterns) 11 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) - Facilitate binding and recognition of interaction between the cell and the B. Complement- they complement the action of antibodies phagocyte a. Fc and complement receptors C. Betalysin- heat stable cationic substance with antibacterial activity (lysis bacteria) - Also recognize IgG and C3b (opsonization) b. Toll-like receptors D. Cytokines- chemical messengers or immunoregulators secreted by leukocytes TLR1- recognizes lipoprotein in Mycobacteria. TLR2- binds to peptidoglycan in Gram-positive bacteria Cytokines with role in Innate immunity TLR3- double stranded RNA virus (dsRNA) TLR4- recognizes lipopolysaccharide in Gram-negative bacteria Pro-inflammatory cytokine; ↑ expression of adhesion molecules on TLR5- flagellin in flagellated organisms IL1 endothelial cells; stimulates the synthesis of addition molecules c. Mannose receptors IL6 Induces acute phase response Recognize carbohydrates in bacterial cell walls leading to the activation of lectin pathway of complement. IL10 Inhibits activated macrophages Not specific receptors in the given microorganism but specific in terms of the nature of the substance IL12 Growth factor for NK and LAK cells Ex. TLR1 recognizes LPP in mycobacteria; this is not specific in particular spp. of mycobacterium. Means any mycobacteria with LPP can be recognized by TLR1 IL15 LAK cell induction; promotes proliferation of NK cells IL18 Synergistic with IL12 5. Non-specific plasma proteins Interferons ɑ Mediate immune response to viral infections Interferons β A. Acute Phase Reactant - Synthesis rate increases during inflammation Mediate inflammatory response to gram-negative bacteria and Tumor necrosis other infectious microbes; capable of lysis of tumor cells PROTEIN INCREASE FUNCTION factor (TNF) CRP (C-reactive protein) 1000x (6-10hrs) Opsonization and activation of the Note: IL12,15,18 - related to NK cells activity classical pathway C. ADAPTIVE IMMUNITY Serum Amyloid A 1000x (24hrs) Removal of cholesterol α1- antitrypsin 2-5x (24hrs) Protease inhibitor 1. TYPES OF ACQUIRED IMMUNITY Haptoglobin 2-10x (24hrs) Binds hemoglobin TYPE MODE OF ACQUISITION Ceruloplasmin 2x (48-72 hrs) Bind Copper and oxidizes iron ACTIVE NATURAL Recovery from infection C3 2x (48-72 hrs) Opsonization, immune clearance ARTIFICIAL Vaccination Fibrinogen 2-5x (24hrs) Clot formation PASSIVE NATURAL Transplacental or via colostrum ARTIFICIAL Serum globulins or antitoxin (RHIG, RHOGAM, HBIG) 12 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) “Adoptive Immunity”- A type of Adaptive; use of soluble mediators to regulate the components of the immune system. Example is LAK Cells - we use soluble mediators like Il2 or IFN gamma in order to activate NK cells into more aggressive form, LAK Cells. 2. VACCINES Stronger localized immunity Immunologic memory Do not often require adjuvants (it potentiates immunogenicity) Live, attenuated or booster doses Mimics natural infection Gives the actual pathogen that has been weekend Induce weak responses Killed/ Inactivated / Variable or poor memory Subunit Usually require adjuvants (potentiate immunogenicity) and booster doses 3. COMPONENTS OF ADAPTIVE IMMUNE RESPONSE Note: Cell-Mediated Immunity (CMI) Humoral Immunity (HI) CMI needs MHC Class I T helper cell Effectors T-cells B-cells & Plasma cells - must be presented in conjunction with MHC Class II to recognize Ag. - Provides help to CMI and HI via CYTOKINE production Mode of action Direct cell-to-cell contact and Antibody production HI- Ab production, but B cells need to be stimulated to undergo Clonal release of soluble mediators Expansion → Differentiation → Plasma Cells & to Memory Cells. Lysis of cells Function Defense against Primary defense against CYTOKINES WITH ROLE IN ADAPTIVE RESPONSE Intracellular antigens (tumor extracellular pathogens such as antigens & viruses) bacteria IFN gamma Major macrophage activator, induces expression of MHC class II molecules Important Event a. Antigen is processed and a. B cells are activated with or presented by macrophages and without T cell cooperation IL2 Tc cell growth factor, production of perforins and IFN-y by Tc cells and NK other APCs b. Activated B cells undergo cells b. Recognition via specific proliferation and differentiation receptors stimulates T cells c. Plasma cells produce IL4 Differentiation of Th0 to Th2, B cell isotype switching c. Th cells secrete lymphokines antibodies while activated Tc cells destroy IL5 Growth and differentiation factor for activated B cells, IgA production antigen-containing cells IL6 T and B cell growth IL10 Inhibits production of other cytokines IL13 Similar to IL4 13 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) Note: ○ shorter lag phase since memory cells recognize the antigen/pathogen IFN gamma & IL2- cytokines produced with Th1 cells Changes in isotype is because of Class Switching (cells that are recognized again IL2, IL4, IL5, IL6, IL10, IL13- cytokines produced with Th2 cells will result in faster and better response) 4. PHASES OF ANTIBODY RESPONSE IV. ANTIGENS AND THE MHC MOLECULES Note: MHC Molecules are also considered HLAs A. CHARACTERISTICS OF ANTIGENS AND IMMUNOGENS 1. Antigen derived from antibody-generating substance capable of binding to antibody (antigen binding portion or a lymphocyte receptor) anything that can bind to an antibody or lymphocyte receptor is Antigenic (but binding may not lead to immune response 2. Immunogen immune response-generating substance Lag Phase no antibody is detectable & no antibody production all immunogens are antigens; but not all antigens are immunogens 3. Epitope starting point of production antigenic determinant Log Phase antibody titer increases logarithmically number of epitope is proportional to the size of the antigen Epitope have a complementary (3D) to the idiotype of an antibody or Plateau Phase antibody titer stabilizes lymphocyte receptor a) Linear Epitopes Decline Phase antibody is catabolized sequential amino acids on a single chain (chains of amino acids) recognized by T-cells 5. PRIMARY vs SECONDARY ANTIBODY RESPONSE Note: T-cells only recognize processed antigens APC process antigens into Linear Epitopes which can be presented to T-cells in association with MHC SECONDARY / ANAMNESTIC Molecules PRIMARY RESPONSE b) Conformational RESPONSE non-sequential amino acids brought into proximity Long lag, short plateau, and rapid Short lag, long plateau, and when protein folds Pattern proteins undergo folding forming tertiary structures decline gradual decline (three-dimensional) Response WEAKER STRONGER found in more complex antigens 4. Hapten Cells Involved Plasma Cells Memory Cells contains a single epitope and only becomes immunogenic when combined with a carrier only one binding site Antibody Type IgM IgG Note: Single epitope (one binding site) is not immunogenic for a molecule to be considered immunogenic, receptors should Antibody Titer Low (descend quickly) Higher (long-lasting) cross-link (large enough bearing multiple epitopes) and bind to a carrier Notes: molecule Memory Cells ○ longer life-span and involved in immunosurveillance 14 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) 5. Adjuvant Heteroantigens that exist in species but are either identical or substance administered with an immunogen to enhance immune closely related in structure so that antibody to one will response cross-react with antigen of the other ○ Aluminum salts Heterophile Weil Felix ○ Freund’s complete adjuvant (not used in humans): contains Antigens ○ screening test for Rickettsia infection mineral oil, emulsifier and inactivated Mycobacteria ○ test use antigens from Proteus (cross react to specific to inactivated vaccines antibodies of Rickettsial infections) Examples: IM antibodies, Forssman, Serum Sickness B. FACTORS THAT AFFECT IMMUNOGENICITY T-dependent require Th cells to stimulate antibody formation antigens 1. Foreignness degree to which antigenic determinants are recognized as nonself directly initiate antibody production predominantly of the IgM Phylogenetic Distance: the more distant the antigen phylogenetically to type T-independent the host, the greater the reaction short-lived and with poor immunologic memory antigens ○ Example: Transplant Example: Lipopolysaccharide (LPS) - gram-negative cell wall 2. Size (directly recognized by B-cells without T- cells) proportional to the number of determinants larger epitopes = more immunogenic bacterial toxins that bind directly to MHC class II molecules and 3. Chemical composition activate Th cells resulting in marked cytokine release, high proteins and polysaccharides are the best immunogens fever, hypotension, and multisystem involvement (multiple organ 4. Molecular complexity failure) complex proteins are better antigens than lipids and nucleic acids Superantigens ○ Cytokine Storm - overwhelming secretions of 5. Structural stability cytokines by activated Th cells must be inert molecules does not undergo processing unstable and inert molecules are poor antigens Examples: TSS Toxins - Staphylococcal & Streptococcal Toxic 6. Degradability Shock Syndrome ability to be processed and presented with MHC molecules D. HUMAN LEUKOCYTE ANTIGENS (MAJOR HISTOCOMPATIBILITY COMPLEX) C. TYPES OF ANTIGENS 1. MHC Classes belong to the host - molecules that are used for antigen presentation to cytotoxic T-cells and Th cells to do not evoke an immune response under normal circumstances facilitate recognition and activation of effector cells (anything that belongs to the body should not stimulate immune Autoantigens response) CLASS I CLASS II Autoimmunity - results from failure of immunologic tolerance; deficiency in T-regulatory cells HLA-A HLA-DR Examples: Autograph & Autologous RBCs Gene Loci HLA-B HLA-DP HLA-C HLA-DQ from other members of the species (relatives) and are capable of eliciting an immune response primarily on APCs (monocytes, ○ HLA alleles Distribution All nucleated cells Alloantigens dendritic cells, activated B-cells) ○ RBC antigens (blood transfusion) clinically important in tissue transplantation and blood Presentation of Presentation of exogenous transfusion Function intracellular/endogenous antigens to antigens to CD4+ Th cells 15 MTAP-1 Immunology and Serology (Discussion of Prof. Balce) CD8+ T cells (cytotoxic Even 1 locus that doesn’t match, will evoke response in the T-lymphocytes) recipient. Organs that are eventually transplanted are not a perfect α chains match that’s why the recipient has to take Chain Structure α and β chains β2-microglobulins immunosuppressants to prevent a necessary graft rejection. Expressed on the surface (used by APC to present antigens to effector refractoriness due to antibodies to class I MHC Expression T-cells Platelet transfusion Transfusion does not serve its purpose (phase was not done because of the antibodies in the host) CLASS III not expressed on the surface (produced by the cells and released) Disease Certain alleles that are linked to the development of immune or complement components C2, C4, Factor B, and TNFα, TNFβ association autoimmune disorders. secreted proteins that have an immune function but are not expressed on cell surfaces HLA Related Disease/s (high percentage) Note: β2-microglobulins - marker for GFR because of its small size; naturally present in the body; freely filtered by glomeruli B27 Ankylosing spondylitis 2. Genetics B8; DQ/DQ8 Celiac disease encoded by MHC genes located on the short arm of chromosome 6 DR2 Multiple sclerosis Naming: capital letter represents gene locus and a number indicates specific alleles DR2/DR3 Systemic lupus erythematosus follows Mendelian inheritance (haplotypes), codominant expression; recombination is rare DR3 Grave's disease, Myasthenia gravis subject to extensive polymorphism - occurrence of two or more alleles of a gene, each with appreciable frequency (>1%) in the same population DR3/DR4 Insulin dependent diabetes mellitus/ Type 1 DM ○ inheritance of MHC genes is subject to extensive polymorphism (many alleles) DR4 Rheumatoid arthritis ○ major barrier to organ transplantation and the reason why it is difficult to find a good match is because of polymorphic nature of MHC genes