Effect of interferon-gamma in experimental Cryptosporidium parvum infection.

The activity of recombinant murine interferon-gamma (IFN-gamma) against infection by Cryptosporidium parvum was evaluated in immunosuppressed rats. Daily intraperitoneal doses of at least 125,000 U/kg significantly (P < .05) reduced the intensity of subsequent ileal infection. In addition, daily administration of 500,000 U/kg significantly (P < .05) inhibited colonization of the biliary tract. When administered for 11 days to rats with established C. parvum infection, IFN-gamma significantly (P < .05) reduced the number of parasites in the small intestine, but this treatment was ineffective against infection of the biliary tract and large intestine. Although the parasite loads in the common bile duct and large intestine were not significantly reduced, there were fewer cases of infection among the treated rats than in the control group. The data suggest that treatment with IFN-gamma may limit cryptosporidiosis of the small intestine.