Whole antilymphocyte serum: a potent safe immunosuppressive agent for intravenous use in man.

Fifty-one renal and marrow graft recipients have been treated with whole, absorbed rabbit anti-human-lymphocyte serum. Such sera are potent nontoxic immunosuppressive agents. Preexisting sensitivity can be erased, and early rejection episodes are essentially eliminated. Prolonged treatment is necessary and safe, and it ensures a sustained depression in circulating T cells. Adaptation between kidney graft and host then occurs, so that the combination of prednisone and Imuran alone can sustain graft viability.