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16 Cards in this Set
- Front
- Back
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Cell mediated immunity and humoral immunity are the 2 aspects of adaptiveimmunity. What mediates cell mediated immunity(CMI)?
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T helper cells(CD4+/CD8-, Th cells, cytotoxic T cells(CD8+/CD4-, Tc cells, macrophages, and natural killer cells.
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What is the major difference between how CMI and humoral immunity are elicited by antigen?
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Unlike the IgM B cell antigen receptor, the T cell receptor(TCR) is not secreted. Immunity must be conferred via direct contact between cells.
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CMI is mainly directed against what 2 major types of cells?
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Cells with intracellular microorganisms and aberrent endogenous cells such as cancer cells.
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Persons with a deficiency in CMI are prone to which types of infections?
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Infections with viruses, fungi, mycobacterium and other intracellular organisms.
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What are the 2 types of naive Th cells? What are their functions?
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Th1 cells mediate the inflammmatory process and activate macrophages. Th2 cells inhibit both the inflammatory process and macrophage activation and aid in helminth immunity and antibody production.
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List te major steps in Th1 cell mediated macrophage activation.
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1. APCs present antigen to naive Th cells leading to Th1 cell differentiation and sensitization in lymph nodes
2. Transit of Th1 cell to site of antigen release(site of infection) 3. Th1 cell activation of macrophages |
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Name the different types of APCs. What 2 signals are needed to activate a Th cell. What cytokine do APCs secrete to induce Th1 cell differentiation?
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B cells, macrophages, and dendritic cells. APCs major histocompatibility complex 11(MHC11) molecule with antigen binds to TCR/CD4 and APCs B7 protein binds to Th cells CD28 providing the necessary costimulation for activation. IL-12 differentiates naive Th cells into Th1 cells.
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Th1 cells migrate to source of antigen(infection) and activate macrophages that present the antigen of interest through what 3 signals?
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Interaction of MHC11 with bound antigen and TCR/CD4, CD40 on macrophage with CD40L on the Th1 cell, and IFN gamma released from Th1 cell with IFN-gamma receptor on macrophage.
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What are functions of macrophages?
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Macrophages present antigens, produce cytokines, and perform phagocytosis.
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What functions of macrophages are enhanced in T cell activation of macrophages?
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Activated macrophages kill phagocytosed microbes via H2O2, O2 and NO, trigger acute inflammation, and facilitate tissue repair by phagocytosis of necrotic tissue.
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Delayed type hypersensitivity(DTH, Type 1V) is the only cell mediated hypersensitivity reaction. Describe and name some examples.
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Previously sensitized T cells reencounter the initial antigen and trigger macrophage activation, a process that develops over 1-2 days. Examples include acute transplant rejections, tbc skin tests, and contact dermatitis.
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Describe the histopathology of a granuloma. In what instances are granulomas produced?
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Granulomas are composed of a central core of activated macrophages surrounded by lymphocytes and are formed in response to persistent antigen stimulation of CMI.
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Activated macrophages in a granuloma are also called epithelioid cells due to morphological changes. What cytokine triggers this change?
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IFN-gamma
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How are T cells activated?
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Requires APC with MHC1 with antigen of interest binding to TCR/CD8 on Tc cell and costimulation by either B7/CD28 or cytokines(IL-2) from Th cells.
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How do activated Tc cells recognize infected cells?
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Through presentation of the antigen of interest on the infected cell by the MHC1 molecule.
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How do activated Tc cells kill infected cells?
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Perforins(create holes in the cells membranes, disrupting osmotic balance), granzymes(activate apoptosis through caspases), and FasL on Tc cells binds Fas on target cells also resulting in apoptosis.
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