THE ROLE OF B-CELLS IN THE DEVELOPMENT OF IMMUNITY TO CRYPTOSPORIDIUM INFECTION

Studies have shown that symptomatic improvement of cryptosporidiosis in immunocompromised patients is possible following treatment with" hyperimmune" colostrum containing anti-sporozoite antibodies from cattle immunized with Cryptosporidium parvum antigens. The contribution to immunity of antibodies developed during Cryptosporidium infection is unclear, however. Previously, we showed that SCID ( severe combined immunodeficiency) mice acquired immunity to C. muds infection if injected with immunocompetent splenocytes. To investigate the role of the splenic donor B-cells in this immunity, groups of CB-17 SCID mice received BALB/c splenocytes, or splenocytes depleted of B-cells by immunomagnetic separation before infection. Both groups recovered from infection at similar times and displayed little difference in patterns of oocyst excretion. Subsequently, B-cells and serum anti-parasite antibodies were found only in mice reconstituted with unfractionated spleen cells. These results suggested that Bcells may not normally be required in immunity against Cryptosporidium.