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23 Cards in this Set
- Front
- Back
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Where do naive T cells first encounter antigen?
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Secondary Lymphoid Tissues (LNs, spleen, MALT)
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Where do naive T cells undergo clonal expansion and differentiation?
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Secondary lymphoid Tissues (LNs, spleen, MALT)
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What is the main function of cell-mediated immunity?
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Elimination of intracellular microbes
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Dendritic Cell Activation: Innate or Adaptive
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Innate
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What do all major mechanisms of immune defense against extracellular bacteria have in common?
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Use of antibodies!
B Cell Activtn Neutralizing Ab's Opsonized Phag Toxin neutralization by antitoxin Complement |
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What is T Cell priming?
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T-cell activation; first stage of primary adaptive immune response
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What are the general functions of T helper cells?
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Secrete Cytokines
Activate other immune cells |
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What cytokine governs clonal expansion? What cell releases this cytokine?
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IL-2 controls clonal expansion (binds IL-2 receptors at T-cell surface to drive clonal expansion of Ag-specific T cells)
IL-2 is released by the activated T cells |
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What are the 2 requirements for the release of IL-2 from a T cell?
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1) T-cell receptor:co-receptor complex signal (MHC:peptide on APC)
2) Co-stimulatory signal via CD28 (to B7 on APC) |
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What is anergy? How do APC's work around this?
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Nonresponsive T-Cell: Antigen recognition by naive T cell in absence of costimulation
APC's release IL-12 to upregulate C7 on Naive T cell, thus providing co-stimulation |
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Function of ICAM? What does it bind to?
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ICAM on APC binds to LFA on Tcell
Allows for tightened interaction of T cell with APC |
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What surface molecule is produced by T helper cells when bound to antigen? Effect of this molecule?
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Produce CD40L which binds CD40 receptor on macs and B cells, thus activating them (macs kill, B cells release Ab's)
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Different classes of Th cells secrete __________
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different forms of cytokines (and perform distinct functions)
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Th1 CD4+ vs Th2 CD4+:
Function Cytokines Released Pathogens Most Effectively Cleared |
Th1: coordinate responses that activate macs and eliminate intracellular pathogens via IFN-gamma; INTRACELLULAR PATHOGENS (viruses, bacteria inside cells)
Th2: function in proliferation and dx/dy of naive B cells; induce production of IgA and IgE IL-4: B Cell-->IgE-->Mast Cell Degranulation IL-5: Eosinophil Activation (kill worm: helminth) EXTRACELLULAR BACTERIA, parasites, toxins |
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What is the differentiation of naive Th cells into Th1 and Th2 cells determined by (specifically)?
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Th + IL-12-->Th-1
Th + IL-4-->Th-2 |
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How do CD4+ and CD8+ T cells contribute to Cell-Mediated Immunity?
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CD4+: activate phagocytes to kill microbes that've been ingested
CD8+: kill any cell harboring microbe or microbial prots in cytoplasm |
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How are activated T cells able to recognize antigen in any tissue in the body in terms of migration ability?
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Process is similar to the migration of neutrophils and macs (increased adhesion molecs on endothelium at site of infection, rolling, entering--squeezing through--endotehlium of peripheral tissues)
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What role do Cd4+ T cells play in cytotoxic and phagocytic activity?
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Cd4+ T cells DO NOT directly lyse or and phagocytose, they direct other cells to perform these tasks
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Specificity of CMI is a function of ________, but elimination of the pathogen is a function of ___________
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lymphocytes = specificity
act'd macs = pathogen clearance |
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Activated Macrophages:
Function Cytokines released, effects |
Act'd macs kill microbes, assist in tissue repair, upregulate MHC II and co-stimulatos which make them better APC's
Cytokines released: TNF, IL-1, chemokines (stimulate inflammn and migration of nphils, monocytes, and effector cells) |
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What events are required for macrophage activation? Method of killing?
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CD40L of Th1 must bind CD40 receptor
Th1 must release IFN-gamma Kills via ROI, NO |
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Beginning with an APC bound to antigen and ending with an activated macrophage, list the cytokines involved in macrophage activation (in order of release).
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APC releases IL-12
Naive CD4+-->Th1 cell Th1 cell releases IFN-gamma |
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CD8+ T Cells: method of killing
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Release lytic granules (modified lysosomes containing perforin and granzyme--both of which are cytotoxins)
Granzymes are SERINE PROTEASES |
