Term
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Definition
| lack of intrinsic factor normally produced by gasttric parietal cells, leads to inadequate B12 absorption which causes DNA synthesis impairment resulting in megaloblastic anemia (ineffective hematopoiesis) |
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Term
Pernicious Anemia
(three autoantibodies) |
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Definition
80-90% have autoanitbody to gastric parietal cells (screen)
75% have autoantibody to intrinsic factor (diagnose)
autoanitbody that prevents binding of IF-B12 complex to its receptor in the ileum |
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Term
Pernicious Anemia
(Immune Mechanism, CF, D, T) |
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Definition
Type IV Hypersensitivity
loss of parietal cells; infiltrate lymphocytes and plasma cells
presence of megaloblastic anemia (high MCV); leukopenia with hypersegmented neutrophils; low serum B12; serum antibodies to parietal cells (screening test) or intrinsic factor (more diagnostic); Shilling test*
high dose vitamin B12 can cure the anemia; but, autoimmune attack on gastric mucosa persists, patients are still at increased risk for gastric cancer |
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Term
| Explain how red blood cells can be destroyed by the immune system |
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Definition
- extravascular hemolysis - opsonization by antibodies or complement by macrophages
- intravascular hemolysis - MAC complex, classical complemetn
- PNH - def. in the enzyme that synthesizes GPI-anchored proteins like DAF and CD59. RBCs lacking these surface proteins are not protected by MAC. PNH patietns are Ham's test positive |
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Term
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Definition
| DAF binds C3b deposited on the RBCs and inhibits binding of Bb, thereby inhibiting formation of C3 convertase and terminating activation of the complement pathway |
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Term
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Definition
| CD59 binds any C5b-8 complex that may form on the RBCs and inhibits addition of C9, thereby inhibiting the formation of MAC |
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Term
Describe warm antibody anemia
(symptoms, antibody, mechanism, cause) |
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Definition
jaundic and splenomegaly
IgG
extravascular hemolysis and partial phagocytosis
idiopathic, caused by SLE, chronic drug therapy or infections, lymphoid neoplasms |
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Term
Describe cold agglutin anemia
(Symptoms, antibody, mechanism, cause) |
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Definition
agglutination of RBCs cause peripheral microvascualr obstruction in boyd parts exposed to cold
IgM (active below 37 C)
IgM binds complement complement and causes intravascular hemolysis, extravascular hemolysis, and partial phagocytosis
idiopathic or caused by infections or lymphoid neoplasms |
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Term
| Two mechanisms of drug-induced immunohemolytic anemia |
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Definition
1. drug acts as antigen or hapten
- the warm antibody binds causes intravascular hemolysis
2. drug causes a break in tolerance
- methyldopa causes patients to produce autoantibodies against their own Rh antigens |
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Term
| Explain the role of Coombs' tests in the diagnosis of immunohemolytic anemia and distinguish between the Direct and Indirect Coombs' tests |
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Definition
Direct Coomb's Test demonstrates the presence of antibodies and/or complement on patient's RBCs
Indirect Coomb's Test is used if DAT is positive. It is used to further test the antibody and its temperature dependence. |
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Term
| Scleroderma (RF, IM, Igs) |
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Definition
- 3x more prevalent in women, HLA-DR52a
- CD4 cells accumulate and relase TGF-B which activates dermal fibroblasts
- ANA, anti-centromere- CREST, anti-topoisomerase- scleroderma |
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Term
| Describe Sjorgen's syndrome (CF, Igs) |
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Definition
- keratoconjunctivitis sicca and xerostoma, sicca syndrome, dysphagia
- ribonucleoprotein antigens |
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Term
| Explain the cellular structure of Peyer's patches |
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Definition
lymphoid follicles covered by speialized epithelium
plasma cells found in lamina propia are primed here |
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Term
| Explain the role of M cells |
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Definition
M cells are specialized eptihelial cells that cover Peyer's patches
actively transport antigens from lumen, across epithelium, into dendritic cell rich area, delivers these antigens to where T and B cells are primed |
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Term
| Describe three molecules essential for lymphocyte homing to the lamina propia |
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Definition
- Tcells in lamina propia express CCR9 and a4B7 adhesion molecule
- MAdCAM-1 expressed by blood vessels in lamina propria, is a ligand for a4B7 integrin |
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Term
| What is the cytokine that influences the isotype switch to IgA? |
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Definition
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Term
| True or false: IgA is an opsonizing antibody? |
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Definition
| no, IgA is a neutralizing antibody |
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Term
| What is a function of IL-6 besides inflammation? |
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Definition
| IL-6 assists in self-renewal and differentiation of SCs into myeloid and lymphoid progenitor cells |
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