Identification and purification of immunosuppressive activity in the urine of rats and a human patient treated with niridazole.

Administration of the antischistosomal compound niridazole to mice, guinea pigs, and humans results in the suppression of several manifestations of cell-mediated immunity. Sera from animals treated with niridazole blocked the in vitro production of migration inhibitory factor (MIF) while niridazole itself was inactive, suggesting that these effects are caused by water soluble mediators. We now report that crude extracts prepared from the urine of rats and a patient receiving nirdazole, but not from pretreatment control urine, similarly suppress antigen-induced inhibition of migration of peritoneal exudate cells from sensitized guinea pigs. With immunosuppressive activity monitored by the direct MIF assay, combined solvent extraction and chromatographic techniques were used to fractionate immunosuppressive activity from the urine of niridazole-treated rats and the patient; the most active fractions, purified about 100-to 1000-fold as compared to methanol-water extracts of dried voided urine, inhibited MIF production at 0.1 to 0.01 ng/ml of assay mixture. These purified fractions also showed immunosuppressive activity by an in vivo assay wherein doses as low as 1 mug/kg injected intravenously (i.v.) into mice suppressed cell-mediated granuloma formation around Schistosoma manisoni eggs. Identically purified fractions prepared from urine of rats and the patient before they received niridazole showed no immunosuppressive activity either in the MIF or in the granuloma assay systems.