Immunosuppressive effect of bredinin on cell-mediated and humoral immune reactions in experimental animals.

Bredinin (BR), an imidazole nucleoside isolated from Eupenicillium brefeldianum was previously reported to prolong kidney allograft survival in dogs. The immunosuppressive effect of BR was studied in experimental animals. In beagles, in vitro responses of lymphocytes stimulated by mitogens or allogeneic cells were suppressed by in vitro BR treatment. BR, given in vivo, also showed an inhibitory action against development of delayed hypersensitivity reaction to tubercle bacilli in guinea pigs or against hemagglutinin production following booster SRBC injection in rabbits. Of note may be the fact that BR was found to have an immunosuppressive potency comparable to that of azathioprine and, in addition, to show a decreased hepatotoxicity compared with the latter.