Immunity: Part IV Acquired Immunity

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Remember: Types of Immunity Innate Acquired – Is the body’s second major kind of defense – Involves the activity of lymphocytes

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A summary of innate and acquired immunity INNATE IMMUNITY Rapid responses to a broad range of microbes ACQUIRED IMMUNITY Slower responses to specific microbes External defensesInternal defenses Skin Mucous membranes Secretions Phagocytic cells Antimicrobial proteins Inflammatory response Natural killer cells Humoral response (antibodies) Cell-mediated response (cytotoxic lymphocytes) Invading microbes (pathogens)

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Types of Immunity

Properties of Immunity 1.Specificity 2.Versatility 3.Memory 4.Tolerance

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Figure 14.16

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Figure 14.12

T Cells & Cell-Mediated Immunity T Cells must be activated by exposure to antigen T Cells recognize antigens when they are bound to membrane receptors of other cells Antigen membrane receptors are called –MAJOR HISTOCOMPATIBILITY COMPLEX PROTEINS Class I MHC Class II MHC

T Cells & Cell-Mediated Immunity MHC Proteins Class I –Found on the surface of all nucleated cells –Peptides produced inside the cell are displayed on the surface by Class I MHC proteins. Class II –Found on the surface of lymphocytes & phagocytes Called ANTIGEN-PRESENTING CELLS (APCs)

Types of T Cells 1.Cytotoxic T Cells 2.Helper T Cells 3.Memory T Cells 4.Suppressor T Cells

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Activation of Cytotoxic T Cells MHC Class I clip

Helper T Cells Activated by exposure to antigens presented by Class II MHC proteins Activated helper T cells perform two functions: 1.Coordinate specific & nonspecific defenses 2.Stimulate both cell-mediated & antibody-mediated immunity Activated helper T cells divide to produce: –More activated helper T cells –Memory T cells helper T cells clip

Memory T Cells Produced upon initial exposure to antigen, but do not respond to the antigen at that time. Provide a no-delay response to any FUTURE exposure to the same antigen –Immediate differentiation into cytotoxic T cells and helper T cells

Suppressor T Cells Activated suppressor T cells dampen the responses of other T cells and B cells –Secrete suppression factors Act after the initial immune response

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Sensitization & Activation of B Cells

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Antibody Structure

Antigen-antibody binding

antibody clip

Antibody (IgG) Function Neutralization Agglutination and precipitation Activation of complement Attraction of phagocytes Enhancement of phagocytes Stimulation of inflammation

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Summary of the Immune Response and Its Relationship to Nonspecific Defenses

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Integration of the Lymphatic System with Other Systems