The renal cortex shows widespread glomerular capillary thrombosis with neutrohpils within the glomerular capillaries. There is often necrosis as well. Areas of interstitial hemorrhage are also encountered.

Hyperacute rejection is a complement-mediated response in recipients with pre-existing donor antibodies. Preformed antibodies develop during a prior exposure of the recipient to donor derived antigens related to blood transfusion, pregnancy or abortion.

Signs arise within minutes to a few days at most following transplant.

Antibody mediated rejection is frequently associated with graft loss although early and less severely affected cases sometimes can be saved by increasing cyclosporine and antilymphocyte antibodies.