EFFECTS OF DEHYDROEPIANDROSTERONE IN IMMUNOSUPPRESSED RATS INFECTED WITH CRYPTOSPORIDIUM-PARVUM

Cryptosporidium parvum is a coccidian parasite that causes diarrheal d isease in animals and humans. Severe cryptosporidial infections were n oted in young adult rats immunosuppressed with the glucocorticosteroid dexamethasone (DEX). B-cell and T-cell responses to the mitogens lipo polysaccharide and concanavalin A, respectively, were depressed in the DEX-treated rats. In addition, DEX treatment suppressed serum IgG lev els, in vitro IgG production, and natural killer cell activities. Prev ious results have shown that DEX-immunosuppressed rats treated with de hydroepiandrosterone (DHEA) exhibit significant reductions in cryptosp oridiosis as determined by monitoring oocyst shedding in the feces and parasite colonization of the small intestine. Results from this study indicated thal B- and T-cell responses to their respective mitogens, serum IgG levels, and in vitro IgG production were greater in DHEA-tre ated immunosuppressed rats than in untreated DEX-immunosuppressed rats infected with C. parvum. Similar results were demonstrated in DHEA-tr eated versus normal control rats infected with C. parvum. These result s suggest that the effects of DHEA in reducing cryptosporidiosis are t he result of a potentiation of the immune system in the immunosuppress ed rats.