Pathology Quiz 3
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- What role does IL-2 play in cell-mediated immunity (T-cell)?
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1. THO binds antigen + B7.
THO then releases IL-2 in autocrine matter to stimulate T cell prolif and T cell apoptosis.
# induction/regulation of Tcells.
2. Stimulates proli/diff of NKC and B cells. - What is function of IL-12 in cell-mediated immunity?
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1. THO diff into TH1.
2. Promotes NKCs.
# intracellular organisms- innate immune & cell-mediated. - What is function of INF-gamma in cell-mediated immunity?
- Produced by T cells and NKCs. Activate macrophages.
- What is function of What is function of TNF-alpha in cell-mediated immunity?
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1. Produced by activated mononuclear phagocytes.
Recruits neutrophils and monocytes to site of infection.
2. Stimulates vascular endothelial cells to express adhesion molecules
3. Induces macrophages & endothelial cells to secrete chemokines. - What is diff b/w Th1 and Th2 responses.
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Th1: Proinflammatory.
Release IL-2, IFN-gamma,TNF-beta.
Hallmark of th1=production of IFN-gamma.
Th2: Anti-inflammatory humoral response/allergic immune response.
Release IL4,5 & 10. - Explain how CD4 T cells activate macrophages.
- Th1 produces INF-gamma which activates macrophages.
- Describe 3 characteristics of the activated Macrophage.
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Activated by IFN-gamma.
1. + expression of FcgammaRI receptors
2. + expression of MHC Class II
3. + production of O2- and water - What is contact sensitivity and give examples.
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T cell-mediated, delayed type hypersensitivity reaction (Type 4)in the skin on contact with a particular chemical agent.
Poison ivy (catechols), cosmetics, metals, clothing. - What is a type II reaction and give example.
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IgG mediated hypersensitivity in tissues. Effector=FcR+ cells (phagocytes, NKC cells).
Ex: Drug allergy, myasthenia gravas. - What is a Type III reaction and give example.
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IgG mediated.
IgG:antigen complex in circulation.
Effectors: FcR+ cells(phagocytes & NK cells),Complement.
Ex: serum sickness, arthus reaction. - Compare complement-mediated cell lysis & antibody-dependent cytotoxicity.
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complement-mediated cell lysis = Kupfer cell and splenic macrophage phagocytosis
^opsonin dependent phagocytosis = complement-mediated cell lysis and phagocytosis ^
antibody-dependent cell cytotoxicity (ADCC) = NK cell killing without phagocytosis - What diagnostic tests are used to evaluate Type II and type III tissue injury?
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Type II: Use immunofluorescence to detect the presence of Ab. Test for foreign substance in blood.
Type III: Use stain immunoflourescence to ID clumps (immune complexes) in tissues. - Give examples of autoimmune disease mediated by autoantibodies by Type 1-4.
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Type 1: none.
2: myasthenia gravis, autoimmune hemolytic anemia, Graves disease, Goodpasture's disease
3: systemic lupus, polyarteritis, post-streptococcal nephritis
4. Type 1 diabetes, MS - Explain autoimmune disease mediated by T cells.
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Lack of CD4+,25+ cells which suppress T cells by cell-cell contact.
Examples are Type I diabetes & MS. - Explain role of MHC in autoimmunity.
- Class I and II MHC vary in their ability to present self. If self isn't presented properly in thymus, the self-reactive cells aren't eliminated. Not a change in positive and negative, but a change in the amount of antigen presented at critical points.
- How is molecular mimicry implicated in autoimmune disease?
- Infectious agents share determinants with self antigens.