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Allograft
same species, different genes
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Xenograft
different species
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What is the strongest immune response alloantigen?
MHC molecules
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What are alloreactive antibodies?
Lymphocytes and Abs that react to alloantigens from transplants
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Which are the 6 most important alleles to match for a successful transplant?
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How many haplotypes does each individual have?
20 (e.g. A-B + C-D)
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What is indirect presentation?
Recipient MHC molecules present peptides from graft to T-cells
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What is direct presentation?
Donor MHC molecules present as self to T-cell
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What cells attack chronic grafts?
T helper cells
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What cells attack acute grafts?
CTL
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Is graft rejection, CMI or Humoral mediated?
Both CMI and humoral
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what is a hyperacute transplant rejection?
- Predisposed antibodies attach alloantigen on graft
- Alloreactive antibodies caused by previous exposure via grafts, transfusion, etc...
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How fast does a HaTR occur?
Minutes
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What two tests are performed to avoid hyperacute transplant rejection?
- ABO typing
- crossmatching tests
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How fast does an acute transplant rejection occur?
7-10 days
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What is the active cell in hyperactive and acute rejection?
- Hyperactive: PMN and platelets
- Actute: Tcells (Th and CTL)
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How fast does chronic rejection occur?
Months to years
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What is the active cell in chronic rejection?
- fibroblasts, GF, and cytokines
- ** irreversible as they lay down scar tissue
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What happens to survival rate as HLA mismatch increases (HLA-A, HLA-B, HLA-DR for 6 total)?
- Survival decreases
- ** heart and liver can survive less matches with immunotherapy
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What are the two steps in successful chronic rejection?
- Smooth muscle proliferation
- Inflammation
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