DEVELOPMENT OF CELLULAR IMMUNE FUNCTIONS IN NEONATAL TO WEANLING MICE- RELATIONSHIP TO CRYPTOSPORIDIUM-PARVUM INFECTION

Lymphocyte phenotypes and cellular immune responses (blastogenesis and production of cytokines) to Cryptosporidium parvum were determined fo r spleen cells taken from BALB/c mice. These parameters were measured in mice at 1, 2, 3, and 4 wk of age, either exposed or not exposed to C. parvum in vivo. The percentage of T cells and the T-helper subset i ncreased from weeks 2 to 4; B cells reached a peak percentage at 2 wk. Blastogenic responses were elevated at 1 wk and declined to a low lev el during weeks 2 to 4. Interferon-gamma production was maximal at 4 w k. No interleukin-5 production was seen. Data obtained were similar fo r cells from mice either exposed or not exposed to C. parvum in vivo. These data indicate that age-related changes, particularly the increas ed percentage of T cells and increased interferon-gamma production, ar e temporally related to the acquisition of resistance to colonization of mice with C. parvum. The data also indicate that these age-related changes occur in the absence of specific exposure to parasite antigens .