bacteriology ch32

bacteriology ch32 - 1 Chapter 32 Specificity - adaptive...

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Chapter 32 Specificity - adaptive immunity can be directed against one specific pathogen or foreign substance among trillions Memory - the adaptive immunity response to a second exposure to a pathogen is so fast that there is no noticeable pathogenesis Humoral immunity - also called antibody-mediated immunity; based on antibody activity Cellular immunity - also called cell-mediated immunity; based on action of specific kinds of T lymphocytes Antigens - elicit an immune response and react with products of that response; most are large, complex molecules; can have several antigenic determinant sites (epitopes) Valence - number of epitopes on an antigen; determines number of antibodies that can combine with antigen at one time Antibody affinity - strength with which antibody binds to its antigen at a given antigen- binding site Avidity of antibody - overall antigen-binding at all antigen-binding sites Haptens - small organic molecules; not antigenic but may become antigenic when bound to larger carrier molecule; e.g., penicillin Cluster of Differentiation Molecules (CDs) - membrane proteins on lymphocytes and other cells (some are receptors); have specific roles in intercellular communication; detection and enumeration used diagnostically; Can be used to determine a cell’s identity (e.g. CD4 = helper T cell) Acquired immunity - type of specific (adaptive) immunity a host develops after exposure to foreign substance or after transfer of antibodies or lymphocytes from an immune donor; can be obtained by natural or artificial means and actively or passively Major Histocompatibility Complex (MHC) - collection of genes that encode MHC molecules; in humans, called human leukocyte antigen (HLA) complex; in mice, called H-2 complex; three classes of MHC molecules; Class I molecules found on almost all types of nucleated cells; Class II molecules found only on antigen presenting cells; Class III molecules include secreted proteins that have immune functions MHC molecules - MHC class I – present peptides that originate in cytoplasm (from viruses, intracellular pathogens); present antigen to CD8+ T cytotoxic cells; MHC class II – present peptides that originated outside of cell (bacteria, viruses, toxins); are taken up by APC’s; Present antigen to CD4+ T helper cells T-Cell Biology - major players in cell-mediated immune response; have major role in B cell activation; function in a variety of regulatory and effector ways; T cells mature in the thymus T-Cell Receptors (TCRs) - recognize and bind antigen; antigen must be presented by antigen-presenting cells (APCs) T-helper (T H ) cells (CD4 + T Cells) T H 0- undifferentiated precursors of T H 1 and T H 2 cells T H 1 cells- produce specific set of cytokines; involved in cellular immunity; responsible for delayed hypersensitivity reactions and macrophage activation
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bacteriology ch32 - 1 Chapter 32 Specificity - adaptive...

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