Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chapter 14 Specific Immunity (adaptive immunity)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Adaptive Immunity  Adaptive immunity includes immunity due to:  Exposure to pathogens  Antibody transfer from mother  Vaccination  Injections of antibodies

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 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.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Cell-mediated immunity involves T cells.  T cells recognize antigens by T cell receptors (TCRs) on the T cell surface. Dual Nature of Adaptive Immunity

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Antigenic Determinants  Antibodies recognize and react with antigenic determinants, called, on an antigen.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Antibody Structure

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 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

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 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

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings IgA Antibodies  Dimer  10-15% of serum antibodies  In secretions  Mucosal protection

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings IgD Antibodies  Monomer  Function not fully understood

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings IgE Antibodies  Monomer  0.002% of serum antibodies  On mast cells, basophils, and in blood  Allergic reactions; lysis of parasitic worms

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Activation of B Cells MHC :

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Clonal Selection

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Activation of B Cells  T-independent antigen:  Provokes antibody production without T cell help.  T-dependent antigen: Requires T cell help

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings T-Dependent Antigens  Helper T (T H ) cell recognizes antigen  Activated T H cells secrete cytokines

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Results of Ag-Ab Binding

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings T Cells  Helper T Cells (also referred to as, or T H, cells)  T cell receptors (TCRs): Recognize antigens and MHC II.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Activation of T H

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings T Cells  Cytotoxic T Cells (CD8, T C ) can differentiate into cytotoxic T lymphocytes (CTLs).  CTLs recognize Ag + MHC I.  CTLs induce apoptosis in target cell.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Destruction of infected cell by a CTL

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Antigen-Presenting Cells (APCs)  Digest antigen  Ag fragments are presented on surface of APC in association with MHC  B cells  Dendritic Cells  Macrophages

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Antigen-Presenting Cells  Activated macrophages: Macrophages stimulated by ingesting Ag or by cytokines.  They have increased and capabilities.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Extracellular Killing  Antibody-dependent cell-mediated cytotoxicity by:  Natural killer cells  Eosinophils  Macrophages

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Extracellular Killing Antibody-dependent cell-mediated cytotoxicity by eosinophils

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Immunological Memory  Antibody is the amount of Ab in serum.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Humoral and Cell-Mediated Immune System