Dose-dependent and schedule-dependent effects of interleukin-12 on antigen-specific CD8 responses

Interleukin-12 (IL-12) has been shown to play a central role in the innate and acquired immune responses. Its activities include enhancement of natura l killer (NK) and cytotoxic T lymphocyte (CTL) activity and promotion of CD 4 Th1 cell development. It has also been shown to provide potent activity a s a vaccine adjuvant in generating antibody and T cell responses. We have i nvestigated the efficacy of IL-12 protein in promoting CD8 T cell responses when it is used as an adjuvant for immunization. Studies using, as antigen , cDNA from an autologous antigen (P1A) as well as studies of responses to vaccinia virus-delivered self (gp100) and non-self (beta-galactosidase) ant igens show that the dose and schedule of IL-12 administration can significa ntly affect adjuvant activity, leading to enhancement or suppression of ant igen-specific responses.