Kinetics of immunoglobulin and specific antibody responses of CBA mice infected with Trypanosoma rhodesiense.

Groups of CBA/CaJ and B-cell deficient CBA/N mice were infected with Trypanosoma rhodesiense EATRO 1886 strain. Survival, parasitaemia, serum Ig levels plus specific trypanosomal IgM and IgG antibodies were assayed and compared during infection. Whereas both strains of mice had similar parasitaemias during the first week of infection, CBA/N parasitaemias were lower than those observed in CBA/CaJ mice during the subsequent study period. Antibody responses, specific for T. rhodesience antigens, peaked on day 10 after infection in CBA/CaJ mice, then rapidly declined. However, antibody responses in CBA/N mice remained elevated throughout the study. In addition, the kinetics of specific IgG and IgM varied in CBA/N mice: IgG antibody was detected on day 4, whereas specific IgM was detected on day 16. This unique relationship between the appearance of IgG and IgM antibody may explain the longer survival observed for B-cell deficient CBA/N mice infected with T. rhodesience.