Niridazole. II. A potent long-acting suppressant of cellular hypersensitivity

Niridazole, a human anthelminthic drug, is shown to be a potent long-acting suppressor of delayed hypersensitivity. Much lower doses than used in the therapy of helminth infections suppressed granuloma formation around Schistosoma mansoni eggs for periods up to 32 days and inhibited delayed footpad swelling in mice previously sensitized with eggs. Marked prolongation of skin allograft survival in mice accross the H-2 area was produced. The drug is administered orally, has been used clinically on a massive scale, and appears to be relatively free of the cytotoxic effects of most immunosuppressive agents.