Cholera toxin (CT) is a very effective immunogen and adjuvant for the induction of mucosal IgA responses in mice. However, molecular and cellular aspects of immunogenicity and adjuvancy of CT in higher mammals are still not known. To address this issue, we examined the immunogenicity of CT by systemic immunization of the non-human primate, rhesus macaques. A female rhesus macaque was intramuscularly immunized with 5 ng of CT and after 14 days, plasma and peripheral blood mononuclear cells (PBMC) were obtained. The levels of CT-specific IgM, IgG and IgA in plasma were tested by indirect ELISA. High titers of CTspecific IgM (2150), IgG (2'89} and IgA (216-2) were detected. Further, when PBMC were subjected for CT-specific ELISPOT assay, high numbers of IgM, IgG and IgA antibody forming cells (AFC) were seen. The aliquot of PBMC were cultured with or without 5 ng of CT-B for 3 days and CD4+ T cells were then purified by FACS. When IFN-y and IL-4-specific ELISPOT assays were performed, elevated numbers of IL-4-specific AFC were detected in CT-B stimulated CD4+ T cells. These results were confirmed by cytokine-specific RT-PCR. These findings suggest that CT can stimulate a Th2 cell cascade which results in the induction of IgA responses in addition to IgM and IgG antibodies in rhesus macaques. This work is supported by NIH grants CMIG AI 35544 and 523244.
|Original language||English (US)|
|State||Published - 1996|
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology