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ADAPTIVE IMMUNITY

ADAPTIVE IMMUNITY. Adaptive immunity. Specific Slow during the primary response, but very fast during the secondary responses memory. Specificity is achieved by BCRs and TCRs Each B cell express a unique BCR and each T cell express a unique TCR Clonal selection!. B cell receptor (BCR).

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ADAPTIVE IMMUNITY

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  1. ADAPTIVE IMMUNITY

  2. Adaptive immunity • Specific • Slow during the primary response, but very fast during the secondary responses • memory

  3. Specificity is achieved by BCRs and TCRs Each B cell express a unique BCR and each T cell express a unique TCR Clonal selection!

  4. B cell receptor (BCR)

  5. HUMORAL RESPONSE Circulating B cells which have not been exposed to the antigen  naive B cells When BCR binds to the antigen, the antigen is internalised by the B cell and presented to the T cells

  6. Activated t cells induce • Cell surface proteins (CD40L) • Cytokines • Activated B cell divide rapidly and differntiate to plasma cell • This events take in germinal centres of lymphnodes and spleen

  7. The first IG is always IgM • Later different cytokines instruct B cells to secrete different IG classes (isotype switching)

  8. IG diversity • Differnt gene segments on different chromosomes encode heavy and light chains • These multigene families are separated by non-coding regions and are brought together with gene rearrengements.

  9. Light chain • V  about 76 • J  5 • C  1 Heavy chains V 123-129 D  27 J  9 C 11 Recombinase activating gene RAG-1 and RAG 2 recombinase responsible for the VDJ recombination

  10. Isotype switching: • IL-4  IgG and IgE • IL-5  IgA • DNA sequences known as “switch sites” are located upstream of heavy constant region on the DNA (M, D, G, E and A) • IgM and IgD do not have switch sites • Affinity maturatin  Somatic hypermutation (random mutationx in V regions)

  11. Cell mediated immunity • CMI is the major component of immune response • T cell are essential cells influencing • Cytokine production, B cell activation, macrophage activation, rejection, killling of tumor or infected cells, DTH

  12. TCR • Gamma-delta TCR bearing cells are found in skin, epitelial and intestinal layers • Antigen recognition is MHC restricted • Alfa-gamma V, D and J; • Beta, delta  V and J rearrengements • No somotic hypermutation

  13. TH17 • CD4+ cells producing IL-17 and 22 • Early immune response to bacteria • Autoimmunity • Immunity against fungi

  14. Treg • CD4+CD25 + • FOXP3

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