Effects on Murine Trichinosis of Niridazole, a Suppressant of Cellular but Not Humoral Immunological Responses

Two groups of mice infected with Trichinella spiralis were treated with niridazole (100 mg/kg), one on alternate days, the other daily. Both regimens failed to influence the numbers of adult worms in the intestines or larvae in the muscles compared with untreated control mice. Mice treated with niridazole daily, but not those treated on alternate days, showed a significant reduction in the inflammatory reaction to larvae in the muscles. Immediate footpad swelling in response to injection of soluble Trichinella larval antigen was not affected by niridazole treatment. Niridazole appears to have a highly selective action on immunological responses suppressing cell-mediated reactions but leaving humoral antibody formation relatively intact. Elimination of worms may require the presence of both cellular and humoral immune mechanisms, while inflammation around larvae in the muscles may be largely a cellular reaction.