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Adaptive Immunity

Adaptive Immunity. Vertebrates only Specificity - recognition modules - BCR, Ab and TCR - gene rearrangement is the source of diversity - clonal selection Small lymphocytes - types and sub-types - functions. Recognition concept Receptor or Antibody molecule

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Adaptive Immunity

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  1. Adaptive Immunity • Vertebrates only • Specificity - recognition modules - BCR, Ab and TCR - gene rearrangement is the source of diversity - clonal selection • Small lymphocytes - types and sub-types - functions

  2. Recognition concept Receptor or Antibody molecule Antigen - structure recognized by an Ab, BCR or TCR Epitope - particular sub-structure of the Ag that is bound Affinity - how much a molecule likes to bind to a structure

  3. Small lymphocyte sub-types B-cells BCR is Immunoglobulin (Ig) Plasma cells - effector cells that secrete Ab T-cells Tc = cytotoxic (CD8+) TH = helper T-cells (CD4+) Th1 (inflammation) Th2 (help B-cells make AB)

  4. Recognition modules of Adaptive immunity B-cell receptor B cells T cells

  5. Native vs Denatured Antigen processing Major Histocomp-atibility (MHC) B-cells T-cell

  6. How does MHC work?

  7. Intracellular pathogens Extracellular pathogens All nucleated cells APC Only immune cells Professional APC APC - Antigen Presenting Cells Professional APC - macrophages - B cells - Dendritic cells

  8. Figure 1-26 MHC class I communicates with Tc cells

  9. Figure 1-27 MHC class II communicates with TH cells Dendritic cells interact with naïve T-cells and initiate differentiation

  10. How do Antibodies work?

  11. Parasitic infection Parasite + Mast cell • Neutralization • Opsonization • Inflammation Inflammation Mast cell activated Expel and/or destroy pathogen

  12. Principles of Adaptive Immunity Diversity Specificity Memory Self-tolerance

  13. Gene Rearrangement is the source of Diversity Germline configuration Diversity Alternative combinations Imprecise joints Different types of chains B-cells - somatic hypermutation In the absence of antigen

  14. Clonal Selection Each cell = one receptor Millions of lymphocytes are generated Small subset will recognize a pathogen Proliferation and differentiation Acquired immunity - the adaptive immunity provided by immunological memory

  15. Figure 1-22 Antibodies are usually very specific

  16. Figure 1-30 Some memory lymphocytes Few specific lymphocytes Many lymphocytes Concept Behind Vaccination

  17. Pre-industrialization infants built immunity naturally • Post-industrialization polio rate increased in adults hence a need for vaccination

  18. Polio Vaccine - Inactive vs Oral “live” version VDPV - vaccine derived polio virus - mutations can lead to polio at extremely low rate

  19. Principle of Self-tolerance B-cells with BCR that bind to self will undergo Apoptosis More complicated scheme of selection for T cells

  20. Selection of T cells Thymocytes Positive selection -Self MHC 3. Negative selection Mechanism of Self-tolerance

  21. Immunodeficiencies Inherited deficiencies e.g. Bubble boy disease Stress induced nutrition, emotional Pathogen caused deficiencies HIV - attacks CD4 T lymphocyte

  22. Figure 1-32 Cells and molecules involved in Hypersensitivity Diseases • IgE • IgG • CD4 TH1 • CD8 CTL

  23. Figure 1-33 Insulin-Dependent Diabetes Mellitus Beta cells of the Islets of Langerhans

  24. Figure 1-34 Inflammatory Adaptive Immune Response Hygiene Hypothesis

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