Hyperacute Rejection: Antibody-Mediated Vascular Occlusion

This simulator models the fastest and most destructive form of transplant rejection: hyperacute rejection, in which antibodies the recipient already carries — from ABO incompatibility or prior HLA sensitization — bind donor endothelial antigens the moment the graft is reperfused. Every bound antigen site activates the complement cascade, triggers platelet and fibrin deposition, and builds a thrombus that narrows the vessel lumen in real time. Tune antibody titer, donor–recipient mismatch severity and complement activity to see why a negative crossmatch before surgery is non-negotiable, and watch how quickly an incompatible graft occludes once binding begins.