Basic Immunology Lecture 2. The Adaptive Immune Response.pptx

Basic immunology: Adaptive immune system The Immune Response Our immune response includes innate and adaptive responses: CD8+ cytotoxic Tcells CD4+ helper Tcells, cytokines Plasma cells, antibodies Adaptive (specific) immunity; Key features; Specificity for particular foreign molecules (antigens = a...

Basic immunology: Adaptive immune system The Immune Response Our immune response includes innate and adaptive responses: CD8+ cytotoxic Tcells CD4+ helper Tcells, cytokines Plasma cells, antibodies Adaptive (specific) immunity; Key features; Specificity for particular foreign molecules (antigens = antibody generators) Memory for most previously encountered antigens, so that the second encounter stimulates a faster and greater response. Cellmediated and antibodymediated adaptive immunity Processing and presentation of exogenous antigens on MHC-II by an antigen presenting cell; eg macrophage or dendritic cell helper T-cells in the lymph nodes by antigens presented on MHC-II by macrophages and dendritic cells. Proliferation and differentiation under the influence of IL-2 induces a clone of daughter cells all able to recognise the same antigen Processing and presentation of endogenous (eg viral) antigen on MHC-I by an infected body cell Activation of naïve CD8 cytotoxic Tcells in the lymph node by specific antigen presented on MHC-I. Proliferation and differentiation generates a clone of cells all able to recognise the same antigen cytotoxic T-cells recognise and bind to infected cells displaying the specific microbial antigen. 1. Perforin causes lysis of the infected cell and granulysin kills the microbe. 2. Granzymes induce apoptosis of the target cell. Antibody-mediated immunity B-cells can be activated by direct recognition of antigen through B-cell receptors or through Thelper cell activation. Activated B-cells undergo clonal expansion to become antibody producing plasma Antibodies=Immunoglobulins Single-Unit antibody structure V; variable domain C; constant domain Antibody classes and functions IgG; A monomer, most abundant antibody in the blood, neutralises bacterial and viral toxins, enhances phagocytosis, and activates complement. Crosses the placenta-fetal immunity. IgA; A dimer, most abundant antibody in sweat, tears, saliva, mucus, milk, protects mucus membranes against Ig IgM adhesion of A virus and bacteria. IgM; A pentamer and first antibody to be secreted by plasma cells following activation. Activates complement, causes agglutination and lysis of bacteria. Antibodies to blood group antigens are IgM. IgE; a monomer, mostly found on mast cells in tissue Immunological memorythe basis for vaccination Thousands of memory cells exist after initial encounter with an antigen - this is called Immunological Memory. – With the next appearance of the same antigen, memory cells can proliferate and differentiate within hours. Serum IgG antibody titers are much higher and much faster on the second response Consolidation and RevisionReading List Tortora and Derrickson; Principles of Anatomy and Physiology Chapter 22; Lymphatic system and immunity https://www.khanacademy.org/science/biology/im munology