Cryptosporidium parvum infection after abrogation of natural killer cell activity in normal and severe combined immunodeficiency mice.

The role of natural killer (NK) cell activity in adult mice with severe combined immunodeficiency (scid mice) infected with Cryptosporidium parvum oocytes was evaluated. Adult BALB/c and scid mice were inoculated intragastrically with 10(6) C. parvum oocysts after the administration of anti-asialo-GM1 or control normal rabbit serum. Groups of animals were evaluated for splenic NK cell activity and examined histopathologically at 2, 4, and 6 wk postinfection. Virtual elimination of splenic NK cell activity by anti-asialo-GM1 treatment was demonstrated. Nonetheless, no differences in the occurrence of illness, death, or histopathologic evidence of infection were observed between anti-asialo-GM1-treated and control-treated BALB/c or scid mice. We conclude that NK cell activity, at least as measured in the spleen, does not play a significant role in murine host defense of cryptosporidial infection, even in the absence of functional B and T cells.