Platelets in hyperacute rejection of heterotopic cardiac allografts in presensitized dogs. An experimental study.

Experiments were carried out to determine whether platelet aggregation plays a primary role in cardiac allograft hyperacute rejection, as has been observed in renal allograft hyperacute rejection. Dogs were presensitized by multiple skin grafts before a cervical heterotopic cardiac allograft was placed. One group of dogs was treated with sulfinpyrazone, a platelet inhibitor, and another was not. In the majority of the untreated dogs, the cardiac transplants were rejected hyperacutely and showed, morphologically, platelet aggregation followed by vascular disruption. In the treated dogs, hyperacute rejection was prevented, but the cardiac transplants were later rejected by primary cellular rejection. These data and the results from the experiments of other researchers lead us to propose that platelets are the "effector" of hyperacute rejection.