Hyperacute rejection is due to:

Ans. a. Preformed antibodies (Ref: Robbins 9/e p233, 8/ep228; Schwartz 9/e p274-275; Bailey 25/e p1408-1412)Hyperacute rejection is due to preformed antibodies.Hyperacute rejection:Immediate (within minutes to hours) graft destruction due to ABO or pre-formed anti-HLA antibodiesQ.Characterised by intravascular thrombosisQKidney transplants are particularly vulnerableQ to hyperacute graft rejection.Types of Graft RejectionHyperacute RejectionAcute (cellular) RejectionChronic Rejection* Immediate (within minutes to hours) graft destruction due to ABO or pre-formed anti- HLA antibodiesQ.* Characterised by intravascular thrombosisQ* Kidney transplants are particularly vulnerableQ to hyperacute graft rejection* Heart and liver transplants are relatively resistantQ.* Occurs during the first 6 monthsQ* Most commonly presents between 5-30Q days after transplantation* T-cell dependent, characterized by mononuclear cell infiltrationQ* Usually reversibleQ* Occurs after the first 6 monthsQ* MC cause of graft failureQ* Non-immune factors may contribute to pathogenesis* Characterized by myointimal proliferation in graft arteries leading to ischemia and fibrosisQ Pathological Features of Rejection ReactionsAcute cellular rejectionAcute humoral rejectionChronic rejection* Interstitial mononuclear cell infiltration with edema* Mild interstitial hemorrhage* Focal tubular necrosis* Endothelitis* Necrotizing vasculitis with endothelial cell necrosisQ* Neutrophilic infiltration* Deposition of immunoglobulinsQ, complement and fibrin* Renal cortical necrosisQ and atrophy* Dense obliterative intimal fibrosis* Interstitial fibrosis* Glomerular loss with tubular atrophy* Shrinkage of renal parenchyma