Contemporary concepts in noncellular rejection

Acute rejection is the major cause of morbidity and mortality in the first year after cardiac transplantation. Cellular rejection is the most common form of rejection observed; however, noncellular rejection is being seen more often. This noncellular rejection is mostly a result of less well-characterized antibody-mediated mechanisms. Antibody-mediated rejection is associated more commonly with hemodynamic compromise, increased graft loss, cardiac allograft vasculopathy, and increased mortality. Histologic, immunofluorescence, and immunoperoxidase studies of endomyocardial biopsies from such patients often reveal intravascular macrophages and immunoglobulin and complement deposition in capillaries, in the absence of lymphoid infiltrates. Severely ill patients require intense therapy, which includes high-dose corticosteroids, cytolytic agents, intravenous heparin, intravenous gamma globulin, plasmapheresis, and/or antiproliferative agents. Further understanding of noncellular rejection will lead to more effective therapy.