Treatment of murine cryptosporidiosis with anticryptosporidial immune rat bile.

Persistent cryptosporidiosis was established in nu/nu BALB/c mice by oral inoculation with Cryptosporidium parvum oocysts. The model was used to determine the impact of anticryptosporidial immune rat bile on the resolution of the disease. Presence of C. parvum-specific IgA in the immune rat bile was determined by enzyme-linked immunosorbent assay. Infection of mice was verified by stool analysis for oocytes and by hematoxylin and eosin-stained intestinal sections from control mice (infected but untreated). Efficacy of treatment was determined in control and treated mice by analysis of identical, hematoxylin and eosin-stained sections of the small intestine and cecum. Semi-quantitative comparisons were made by determining the percent of crypts infected with Cryptosporidium organisms. The scores of treated mice were significantly lower then controls. Microscopic analysis of intestinal sections showed less villus atrophy, crypt hyperplasia, and fewer organisms per crypt in the immune bile-treated mice than in controls. These results support a role for humoral immunity in the eradication of cryptosporidiosis.