SUPPRESSION OF TISSUE IMMUNITY BY CYCLOPHOSPHAMIDE

Abstract

Cyclophosphamide, like other alkylating agents, has marked inhibitory effects on humoral antibody formation. The present experiments were designed to assess the effectiveness of cyclophosphamide in prolonging skin homograft survival in mice, to determine action in relation to dosage, frequency of administration, and time of commencement of treatment. Maximal prolongation was obtained by repeated intraperitoneal administration, started on the day of, or 3 days before, grafting. Graft survival was increased from 10.5 days in controls to 16 days in injected mice (across the H-2 histocompatibility barrier). Cyclophosphamide was employed in 4 cases of human cadaveric renal homotransplantation. One patient has survived 12 months and another 5 months after grafting. These findings suggest that cyclophosphamide has an effect in suppressing cellular immunity in the human being.