immunology Flashcards
types of transplant rejections
hyperacute, acute, chronic and graft vs. host
when does hyperacute rejection manifest
within mins to hrs of the transplant
How does hyperacute rejection manifest
widespread thrombosis with ischemia and necrosis
Pathogenesis of hyperacute rejection
preformed recipient Abs reacting to donor antigen (type II hypersensitivity) which activates complement and clotting cascade: i.e. type A recipient will have preformed anti-B Abs that will recognize graft from a type B donor
treatment of hyperactue rejection
remove graft
when does acute rejection manifest
weeks to months
cellular mediated pathogenesis of acute rejection
CD8 cytotoxic T cells activated and MHC class I comples on donor cells
humoral mediated pathogenesis of acute rejection
Abs formed against donor tissue, but they are not preformed
histologic changes of acute rejection
lymphocytic infiltration with vasculitis of donor vessels
prevention of acute rejection
immunosuppressants
timeline of chronic rejection
months to years
pathogenesis of chronic rejection
cellular and humoral: recipient CD4 T cells respond to donor antigens presented by recipient APC releasing cytokines
histologic changes of chronic rejection
vacular smooth muscle proliferation with parenchymal fibrosis; dominated by arteriolosclerosis
pathogenesis of graft v host
donor T cells proliferate in the immunocompromised host and reject recipient cells as foreign
setting in which graft v host is seen
Bone marrow transplantation; sometimes liver transplant
potential beneficial in leukemia
