Fundamentals of Immunology PDF

BLOOD BANKING MT TERM LECTURE \ CAYACAP 06...

BLOOD BANKING MT TERM LECTURE \ CAYACAP 06 MODULE 2: FUNDAMENTALS OF IMMUNOLOGY ROLE OF THE IMMUNE SYSTEM OUTLINE Work of the immune system can be divided into 2 I Immune System A Definition of Terms separate but compatible roles: II Role of the Immune System o Defense against o While, III Overview of the Immune System foreign, keeping abnormal A Self Antigens vs Non-Self external organisms damaged cells IV Innate and Acquired Immunity and objects from causing havoc V Cells & Organs of the Immune System In blood banking or transfusion medicine, the major A T Cells focus of understanding the immune system has been in B B Cells C Other Cells the areas of antigen and antibody reactions, VI Characteristics of Immunoglobulins including indirect & direct antibody screening and A Immunoglobulins (Antibodies) crossmatching. B Immunoglobulins Significant in Blood Banking o Identification or understanding of the different C Immunoglobulin Variation characteristics of an antibody and on the typing of VII Factors Affecting Ag-Ab Reactions RBC antigens A Distance o Ex. We want to know if this antibody is capable of B Antigen-Antibody Ratio reacting at body temperature → if it’s cold reactive C pH D Temperature or can be destroyed by the enzymes E Immunoglobulin Type o Having an understanding of these concepts and its VIII Factors that Influence Agglutination Reactions reaction is essential to understanding the factors A Centrifugation that can affect agglutination reactions between red B Antigen-Antibody Ratio cells and antibodies during the different testing C pH phases. D Temperature E Immunoglobulin Type Usually, three testing phases in Blood Banking: F Enhancement Media o Immediate Spin Phase o 37 Degrees Celsius Phase o AHG Phase IMMUNE SYSTEM One of the most interesting, complex, and important OVERVIEW OF THE IMMUNE SYSTEM systems in the human body because it serves to To be able to destroy invaders, the immune system protect us from foreign substances. must first recognize them – the immune system must be able to distinguish what is non-self vs self antigens TERM DEFINITION SELF ANTIGENS ü Anything that is derived from the IMMUNOLOGY ü Study of our body’s immune host genome system NON SELF ü Refers to anything physically IMMUNITY ü State of being immune outside the host whether it is a ü A process that occurs to defend living organism or a non-living the human body against foreign toxin organisms or molecule ü Ranges from bacteria, ü It is very necessary to protect parasites, fungus, poison ivy the host from obvious invaders and insect venom such as parasites and also A very important concept of the immune system is the external noxious elements Innate Immunity vs the Acquired Immunity and sun exposure IMMUNE ü AKA Immunotolerance INNATE ACQUIRED TOLERANCE ü Happens when there is too IMMUNITY IMMUNITY much immune engagement – OTHER NAME Natural Immunity Adaptive Immunity this may start to inactivate the IMMUNOLOGIC NONSPECIFIC, SPECIFIC, immune system RESPONSE present at birth specialized ü If tolerance will develop against antigens on transfused cells IMMUNOLOGIC ABSENT PRESENT or transplanted cells, the MEMORY immune system will no longer respond when it encounters the INNATE AND ACQUIRED IMMUNITY same antigen again even if they are present on a different cell or INNATE IMMUNITY tissue this time around Less complicated, but more primitive ü State of unresponsiveness to Recognize patterns of complexity present on common a specific antigen invading organisms (ex. lipopolysaccharides) IMMUNE ü Immune system may neither Immediate line of defense IGNORANCE elaborate an effective response Does not need modifications; not altered in any way against an antigen nor become no matter how many times one is exposed to the same tolerant of it antigen ü Phenomenon in which patients’ Destroy pathogens through phagocytosis, or immune system already fails ingestion, or through the production of cytocidal to mount a productive immune compounds such as reactive oxygen. response TRANS BY: ABELLA | 3A-MT 1  TRANS: Fundamentals of Immunology PARTS OF INNATE IMMUNITY Repeat exposure would yield a stronger immune response from the acquired immunity due to the 1. PHYSICAL Includes: BARRIERS presence of immunologic memory. o Epithelial cells à intact skin o Trapping of bacteria in the mucus TYPES OF ADAPTIVE IMMUNITY 2. BIOCHEMICAL These are chemicals secreted by 1. ACTIVE ADAPTIVE IMMUNITY BARRIERS / cells and tissues such as: The host gains an active adaptive immunity when MEMBRANES o Acidic pH of the skin surface given or introduced to an antigen to stimulate o Complement immune response against that specific antigen in o Interferons future instances. o Lysozymes 3. PHAGOCYTES These are the polymorphonuclear MODE OF ANTIBODY DURATION cells and mononuclear cells. ACQUISITION PRODUCED OF BY THE HOST RESPONSE 4. OPSONINS These are substances that enhance phagocytosis NATURAL ACTIVE 5. COMPLEMENT It is composed of a collection of 20 (exposed to a SYSTEM circulating serum proteins which foreign Infections Yes Long* has 3 major roles in immunity: immunogen as 1. Responsible for the final a result of infection) lysis of the pathogenic cells ARTIFICIAL via antibody binding ACTIVE 2. Opsonization and (exposed to a phagocytosis foreign 3. Mediation of inflammation immunogen in Vaccination Yes Long* response to These serum proteins are altered/non- enzymes that are normally found infectious in the plasma in a proenzyme organisms) inactive state and can be *It takes long because you are still producing antibodies against the activated through the 3 antigen pathways: 2. PASSIVE ADAPTIVE IMMUNITY Classic Activated by an The host gains a passive adaptive immunity when Pathway antigen-antibody given an antibody to stimulate immune response. binding Alternative Activated by means MODE OF ANTIBODY DURATION Pathway of recognition of ACQUISITION PRODUCED OF polysaccharides and BY THE HOST RESPONSE lipopolysaccharides In vivo NATURAL found on bacteria transfer of No Short* PASSIVE and tumor cell antibodies surfaces. Infusion of Lectin Activated by ARTIFICIAL PASSIVE plasma/serum, No Short* Pathway mannose binding Vaccination proteins bound to *It is shorter because the body does not need to produce any antibody macrophages. as it already given The end product of complement activation of any of these 3 CELLS & ORGANS OF THE IMMUNE SYSTEM pathways is always cell lysis and T CELLS ü The T-cells comprise 80% of the inflammation. circulating lymphocytes in the body, and they mature in the Thymus. ü They are responsible for making INFLAMMATION cytokines and destroying virally Inflammation resulting from the activation of the infected cells. complement system is initiated by tissue damage which will result to an increased blood flow to the T Cell- Is involved in the response wounded area. mediated against fungal and viral o There is an increased vascular permeability to the immunity infections, intracellular area causing the mobilization of active cells to the parasites, tissue grafts, site. and tumors. 5 cardinal signs of inflammation: T-Cell Do not recognize 1. Rubor (redness) Receptors foreign antigen on 2. Calor (heat) their own, as B cells 3. Tumor (swelling) do. 4. Dolor (pain) They require help in 5. Functio laesa (loss of function) the form of cell membrane proteins known as Major ACQUIRED IMMUNITY Histocompatibility Adaptive or specific type of immunity since it appears Complex (MHC) only after a specific antigen is encountered, and it Molecules responds specifically to that antigen. It is more advanced and most regarded, and is only There are two (2) Major types of MHC: present in vertebrates. MHC Found on most of the Formation of Ag-Ab complexes Class I Nucleated cells TRANS BY: ABELLA | 3A-MT 2  TRANS: Fundamentals of Immunology Associated to the o Peyer’s Patches Cytotoxic T-cells (CD8) o Mucosa-associated MHC Found on most Antigen- lymphoid tissues Class II Presenting Cells Associated with T-helper CHARACTERISTICS OF IMMUNOGLOBULINS cells (CD4) IMMUNOGLOBULINS (ANTIBODIES) B CELLS ü Comprises 20% of the circulating lymphocytes, and they mature in the Produced by plasma cells (activated B cells), that bone marrow. has specificity to immunogens that stimulate their ü Upon stimulation by an antigen, they production. evolve into plasma cells that secrete a o Antibodies are specific for an antigen or an specific type of antibody for its lifetime. immunogen. ü PLASMA CELLS: Antibody factories FUNCTION: Bind antigen, fix complement, facilitate phagocytosis, and neutralize toxic substances in the circulation. OTHER CELLS OF THE IMMUNE SYSTEM They are classified according to the molecular Antigen- ü These cells first phagocytize the structure of their heavy chains. Presenting foreign antigen and process them o IgG > IgA > IgM > IgD > IgE Cells (APC) internally. Upon processing, these antigens are divided, becoming ANTIBODIES / TYPES OF IMMUNOGLOBULINS short peptide sequences with the help of the MHC molecules. IgG ü Is the most predominant antibody, and the ü After the processing of these major antibody in secondary immune antigens with the help of MHC response. molecules, these short peptides are ü It is the only antibody that crosses the then presented on the surface of placenta. the cell membranes. ü Most significant Antibody in transfusion o The T Helper cells can then medicine recognize the antigen in the ü Most concentrated antibody in blood bank context of MHC presentation IgM ü It is the largest antibody considered as the and respond to it by the primary response antibody. appropriate immune ü It is the best at agglutinating reactions and reaction. the activation of its complement because of ü Examples of APCs: the size. Macrophages Langerhans cells ü Most commonly encountered antibody in the Neutrophils Glial cells ABO system Some B cells Kupffer cells IgA ü It is predominantly found in bodily Osteoclasts secretions Natural ü These are cells that can kill tumor IgE ü It is responsible for allergic reactions Killer Cells cells or cells infected with a virus. IgD ü Acts as a cell membrane surface Dendritic ü Involved in Antigen Processing component of B-lymphocyte together with Cells the monomeric IgG. IMMUNE SYSTEM ORGANS IMMUNOGLOBULIN STRUCTURE These are the different immune system organs associated 1. Four Polypeptide chains with the Acquired Immune System. 2. Two Identical Light chains 3. Two Identical Heavy chains LYMPHOID ORGANS ASSOCIATED WITH THE 4. Disulfide bonding holding both heavy and light chains ACQUIRED IMMUNE SYSTEM PRIMARY LYMPHOID SECONDARY LYMPHOID WHAT ARE THE TWO TYPES OF LIGHT CHAINS? ORGANS ORGANS Kappa Lambda Thymus Lymph nodes Bone marrow Spleen IMMUNOGLOBULINS SIGNIFICANT IN BLOOD Mucosa-associated BANKING tissues 1. IgG React BEST at body temperature (37C) ü Site of maturation for T ü Site of cell function for Very significant in transfusion medicine and B cells mature T and B cells because it can cause hemolytic transfusion ü Lymphocytes ü Cells interact with each reactions and hemolytic disease of the differentiate from stem other and with accessory newborn because they are capable of cells, then migrate to cells and antigens destroying transfused antigen positive red secondary lymphoid cells. organs Has the greatest number of subclasses (1 to 4) 1. PRIMARY Site of lymphocyte Functional difference in subclass: LYMPHOID maturation o Ability to fix the complement ORGANS Thymus – T Cells o Crossing the placenta Bone Marrow – B Cells 2. IgM Reacts BEST at cold temperature (4-22C) 2. SECONDARY Site of lymphocyte activation Usually masks agglutination of clinically LYMPHOID This includes the following: significant IgG ORGANS o Lymph nodes o Covers the agglutination of weakly o Spleen reacting IgG which can be very o Tonsils dangerous o Appendix TRANS BY: ABELLA | 3A-MT 3  TRANS: Fundamentals of Immunology To Perform ADSORPTION of IgM temp) or IgG (body temp prevent antibodies if clinically or 37C) this / To significant IgG antibodies are 5. IMMUNOGLOBULIN TYPE remedy being suspected (for optimum detection) IgM Has the potential to bind 10 separate Molecule antigen sites because it’s a pentamer o Sulfhydryl reducing agents like 2- Capable of agglutinating red cells in 0.85% NSS mercaptoethanol (2-ME) or Capable of agglutinating in the Dithiothreitol (DTT) can dissociate immediate spin phase already IgM through the cleavage of covalent IgG Has only 2 binding sites per molecule bonds - these reagents can remove Molecule Requires enhancement media, reacts IgM so IgG can be detected. during the AHG phase 3. IgA 30% of anti-A and anti-B antibodies are of 6. ENHANCEMENT Antibodies reacts best at the IgA class MEDIA 37C and are generally Increase the effect of IgG-induced RBC responsible for hemolytic hemolysis transfusion reactions and Note: These antibodies are capable of destroying transfused HDN, these are the IgG antigen positive red cells and can cause anemia and other antibodies. transfusion reactions of various severities. To discover the presence of IgG antibodies there are IMMUNOGLOBULIN VARIATION many enhancement media Determines the antigen binding specificity of the antibody or techniques or ISOTYPE ü AKA class variation potentiators available. ü Variations between LIGHT and It is usually aimed to detect HEAVY chains IgG antibodies ALLOTYPE ü Different ALLELES of HEAVY It reduces the zeta potential chains of the RBC membrane. IDIOTYPE ü Variation in the VARIABLE region Examples: o CHON Media (Protein FACTORS AFFECTING Ag-Ab REACTIONS media) 1. DISTANCE o Low Ionic strength 2. ANTIGEN- We have to achieve the media ANTIBODY RATIO zone of equivalence as to o Enzymes prevent post-zone and o AHG (Anti-human prozone phenomenon globulin) which can cause false negative reactions 3. pH 4. TEMPERATURE IgM: Antibody that best REFERENCES reacts at cold temperature Notes from the discussion and PPT by Eunice Fay IgG: Best reacts at body Cayacap, RMT temperature 5. IMMUNOGLOBULIN IgM: Antibody that is best TYPE in agglutination reaction FACTORS THAT INFLUENCE AGGLUTINATION REACTIONS 1. CENTRIFUGATION Simplest and most common technique to enhance agglutination. Decreases reaction time by increasing the gravitational forces on the reactants and bringing the reactants closer together. 2. ANTIGEN- Zone of Equivalence must ANTIBODY RATIO be achieved PROZONE Any excess of EFFECT unbound Antibody POST-ZONE Excess EFFECT Antigen Both effects don’t have lattice formation causing false negative reactions. 3. pH It should be set between 6.5 - 7.5, which is similar to the pH of normal plasma or serum 4. TEMPERATURE Important to test with a wide range of temperatures because we may be dealing with IgM (cold/ambient TRANS BY: ABELLA | 3A-MT 4