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16 Cards in this Set
- Front
- Back
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Humoral immunity and cell mediated immunity are the 2 branches of adaptive immunity. What mediates humoral immunity, and what are the targets?
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HI is a B cell and antibody mediatede response directed against extracellular microbial pathogens(encapsulated bacteria), certain intracellular microbial pathogens(viruses) and microbial toxins.
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What is the difference between the recognition phase and effector phase of humoral immunity?
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The recognition phase involves the identification of antigens via membrane bound immunoglobulins(IgM and IgD) on the surface of the naive B cell. The effector phase is characterized by secretion of immunoglobulins from plasa cells(mature B cells).
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A primary response is generated when an antigen is first encountered. Second exposure to the same antigen is known as the 2ary response. What are the key differences between a primary and 2ary response?
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Theprimary response has a longer lag period(time until antibody is produced) and is typically characterized by IgM followed by low amounts of IgG. The 2ary response is characterized by a faster and larger production of IgG that persists longer. These differences aredue to antigen specific memory B cells in the 2ary response.
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What is affinity maturation?
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Process that selects for B cells producing antibodies of highest affinity to an antigen of interest through successive exposure to that antigen in the periphery.
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What genetic process drives affinity maturation?
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Somatic hypermutation results in random and rapid points mutations in variable gene segments of V(D)J genes, modifying the affinity of a B cells Ig. The B cells expressing Igs with highest affinities are then selected through interaction with antigen.
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What is the name of the process by which immature b cells expressing Igs with a high affinity for self antigens are restricted from becoming mature?
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Negative selection. An analogous process occurs with T cells.
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What type of cell stimulates B cell clonal expansion, isotype switching, affinity maturation, and differentiation into memory B cells?
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Helper T cells(CD4+/CD8-)
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What are the 2 types of cells that activated B cells may become?
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Plasma cells, which are responsible for secretion of antibodies, and memory B cells, which undergo affinity maturation and may differentiate into plasma cells upon reexposure to the antigen.
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Will as single antigen with a single antitope activate a B cell?
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No. B cell activation is dependent on the cross linking of membrane bound IgM and IgD, which requires more than 1 epitope.
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How do B cell and T cell receptors differ with respect to the native form(3 dimensional shape) of the antigen?
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T cell receptors recognize only a linear peptide sequence that results from processing within an APC. The B cell receptors can recognize the native form of the antigen.
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B cell proliferation, early body secretion, and isotype switching occurs in which area of the lymphoid follicle?
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These early phase T cell dependent responses occur in the marginal zone.
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B cell affinity maturation and isotype switching occur in which area of the lymphoid follicle?
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These late phase events occur in the germinal centers. Isotype switching can occur in the early or late phases and in 2 separate locations.
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What processes result from interaction of CD40 on B cells with CD40L on T cells?
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Isotype switching, B cell activation, and affinity maturation. The T cell cytokines also play a role in these processes.
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What cytokine expressed by T cells also cause isotype switching to IgA?
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IL-5
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What is a hapten. How are antibodies generated against haptens?
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Haptens are small chemicals that are nonimmunogenic. Haptens complex with a carrier protein such that T cells can recognize the hapten-carrier protein complex and activate B cells to generate antihapten antibodies.
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When in conjunction with TCR-MHC-11 binding, interaction of the CD28 on the T cell with B7 on a B cell or other APC results in what process in T cell mediated immunity?
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Activation of the T cell, causing the secretion of cytokines from the T cell.
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