B cells are required for the induction of intestinal inflammatory lesions in TCR alpha-deficient mice persistently infected with Cryptosporidium parvum

Mice with targeted disruptions in the T-cell receptor alpha gene (TCR alpha (-/-)) spontaneously develop inflammatory intestinal lesions with extensiv e B-cell lamina propria infiltrates. Cryptosporidium parvum infection accel erates intestinal lesion formation in TCR alpha (-/-) mice, in the present study, TCR alpha (-/-) mice were crossed with JH(-/-) (B-cell-deficient) mi ce and challenged with C. parvum to determine if B cells are required for i ntestinal lesion development. TCR alpha (-/-) x JH(-/-) mice challenged wit h C. parvum, either as neonates or adults, became persistently infected, wh ereas TCR alpha (-/+) x JH(-/+) heterozygote control mice cleared the paras ite. Cryptosporidium parvum colonization of TCR alpha (-/-) x JH(-/-) mice was heaviest in the distal ileum, with fewer parasites detected in the cecu m and distal colon. Despite persistent infection, TCR alpha (-/-) x JH(-/-) mice did not develop inflammatory or hyperplastic intestinal lesions as de tected in C. parvum-infected TCR alpha (-/-) mice. These findings demonstra te that B cells are a necessary component fur the development of inflammato ry intestinal lesions of C. parvum-infected TCR alpha (-/-) mice.