Madrenas_01

Matching is ideal but highly unlikely given

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Unformatted text preview: munobiology 8 – Garland 2012 •  An#gens other than class I and class II MHC molecules that are different between donor and recipient •  Encoded by polymorphic proteins (e.g., male- specific, Smcy- derived pep#des) •  Usually presented in the context of MHC class I molecules •  Trigger a less rapid gra; rejec#on •  DIRECT: –  T cell recogni#on of foreign MHC molecules on foreign APCs (“passenger leukocytes”), which have migrated from the gra; to a secondary lymphoid organ through the blood •  INDIRECT: –  T cell recogni#on of pep#des from allogeneic proteins presented by self- MHC molecules on self APCs Janeway’s Immunobiology 8 – Garland 2012 •  Direct allorecogni#on is thought to be the primary meditator of acute allogra; rejec#on •  Indirect allorecogni#on likely contributes to gra; rejec#on: –  by enhancing macrophage ac#va#on which enhances inflammatory response, #ssue injury and gra; fibrosis –  Likely involved in an#body- mediated acute gra; rejec#on –  May be predominant mechanism of acute xenogra; rejec#on •  Hyper- acute •  Acute •  Chronic •  Mediated by pre- formed (“natural”) an#bodies (usually IgM) against MHC an#gens or blood group an#gens on endothelial cells of allo/xenogra; •  An#body binding causes massive C ac#va#on, endothelial injury, coagula#on, and thrombosis •  Leading to the destruc#on of the organ within minutes of implanta#on •  Currently very rare: prevented by ABO matching and donor:recipient crossmatching •  Differen#al organ suscep#bility: kidney >>> liver Janeway’s Immunobiology 8 – Garland 2012 hLp://www.wikidoc.org/index.php/File:Acute_Transplant_Rejec#on_1.jpg hLp://www.bioscience.org/1996/v1/d/cooper1/htmls/248- 265.htm •  Usually takes place between 3- 5 days a;er transplanta#on •  Role of Ischemia- Reperfusion Injury in sepng up adap#ve alloresponse? •  Ini#ated by ac#va#on of alloreac#ve T cells •  It can be mediated by: –  T cells –  An#bodies: an#- class I an#body mediated –  NK cells Normal Kidney Rejected Kidney •  Requires T cells: Janeway’s Immunobiology 8 – Garland 2012 –  Not observed in T cell deficient individuals –  Can be induced by transferring T cells •  It is accelerated by previous sensi#za#on to the gra; an#gens •  Both major T cell subsets (CD4+, C...
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