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Chapter 14

Chapter 14. Specific Immunity (adaptive immunity). Adaptive Immunity. Adaptive immunity includes immunity due to: Exposure to pathogens Antibody transfer from mother Vaccination Injections of antibodies. Dual Nature of Adaptive Immunity.

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Chapter 14

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  1. Chapter 14 Specific Immunity (adaptive immunity)

  2. Adaptive Immunity • Adaptive immunity includes immunity due to: • Exposure to pathogens • Antibody transfer from mother • Vaccination • Injections of antibodies

  3. Dual Nature of Adaptive Immunity • Humoral immunity involves antibodies produced by B cells. • B cells recognize antigens by antibodies on the surface of the B cells.

  4. Dual Nature of Adaptive Immunity • Cell-mediated immunity involves T cells. • T cells recognize antigens by T cell receptors (TCRs) on the T cell surface.

  5. Antigenic Determinants • Antibodies recognize and react with antigenic determinants, called , on an antigen.

  6. Antibody Structure

  7. IgG antibodies • Monomer • 80% of serum antibodies • Fix complement • In blood, lymph, and intestine • Cross placenta, protects fetus and newborn • Enhance ; neutralize toxins and viruses

  8. IgM Antibodies • Pentamer • 5-10% of serum antibodies • Fix complement • In blood, lymph, and on B cells • microbes; first Ab produced in response to infection

  9. IgA Antibodies • Dimer • 10-15% of serum antibodies • In secretions • Mucosal protection

  10. IgD Antibodies • Monomer • Function not fully understood

  11. IgE Antibodies • Monomer • 0.002% of serum antibodies • On mast cells, basophils, and in blood • Allergic reactions; lysis of parasitic worms

  12. Activation of B Cells MHC:

  13. Clonal Selection

  14. Activation of B Cells • T-independent antigen: • Provokes antibody production without T cell help. • T-dependent antigen: Requires T cell help

  15. T-Dependent Antigens • Helper T (TH) cell recognizes antigen • Activated TH cells secrete cytokines

  16. The Results of Ag-Ab Binding

  17. T Cells • Helper T Cells (also referred to as , or TH , cells) • T cell receptors (TCRs): Recognize antigens and MHC II.

  18. Activation of TH

  19. T Cells • Cytotoxic T Cells (CD8, TC) can differentiate into cytotoxic T lymphocytes (CTLs). • CTLs recognize Ag + MHC I. • CTLs induce apoptosis in target cell.

  20. Destruction of infected cell by a CTL

  21. Antigen-Presenting Cells (APCs) • Digest antigen • Ag fragments are presented on surface of APC in association with MHC • B cells • Dendritic Cells • Macrophages

  22. Antigen-Presenting Cells • Activated macrophages: Macrophages stimulated by ingesting Ag or by cytokines. • They have increased and capabilities.

  23. Extracellular Killing • Antibody-dependent cell-mediated cytotoxicity by: • Natural killer cells • Eosinophils • Macrophages

  24. Extracellular Killing Antibody-dependent cell-mediated cytotoxicity by eosinophils

  25. Immunological Memory • Antibody is the amount of Ab in serum.

  26. Humoral and Cell-Mediated Immune System

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