This is a second-set response where the transplanted organ contains antigens to which the recipient has developed cytotoxic antibodies from previous sensetization. These may be naturally occuring antibodies such as those against the blood group A and B antigens, or they may be antibodies produced against a specific antigen following previous blood transfusion, pregnancy or transplantation.
The binding of the cytotoxic antibody to the antigen in the transplant causes complement activation, endothelial cell activation/disruption, platlet activation and intravascular thrombosis.
Graft destruction occurs within a few hours of engraftment, often before the operation has been completed.