| Abstract: | Experimental evidence that medroxyprogesterone acetate (MPG) prolongs survival of rabbit skin allografts and the survival of dogs with renal allografts has been reported previously. Reviewed in this study are additional experience with MPG and evaluation of melengestrol acetate (MGA), a more potent progestin. Skin grafts were exchanged between New Zealand white and California rabbits of both sexes. Recipients were treated with intramuscular injections of MPG, 50 mg/ml; MGA, 50 mg/ml; estradiol cypionate, 2 mg/ml; horse antirabbit thymocyte globulin (ALG); or combinations of these agents. MPG or MGA significantly prolonged survival of rabbit skin allografts. Large doses of MPG also prolonged survival of dogs with renal allografts, but MGA did not. Rabbit skin allografts survival was further enhanced when MPG was combined with estradiol or when suboptimal doses of MPG and MGA were combined with a suboptimal dose of ALG. When MPG or MGA were combined with azathioprine, a marked prolongation on survival of dogs with renal allografts was observed. In a preliminary trial of MPG in humans with intrafamilial renal transplants, chronic slow rejection was not halted by addition of MPG to the immunosuppressive regimen. In patients whose renal function was stable at the time of initiation of MPG therapy, prednisone dosage could be lowered to an average of 37% of the previous dose and the patient's Cushingoid appearance or aseptic necrosis of the hips either did not progress or improved. |
