OXIDATIVE REDUCTIVE CONJUGATION OF MANNAN TO ANTIGEN SELECTS FOR T-1 OR T-2 IMMUNE-RESPONSES

The induction of CD8(+) cytotoxic T lymphocytes (CTLs) is desirable for immunization against many diseases, and recombinant-synthetic peptide antigens are now favored agents to use, However, a major problem is how to induce CTLs, which requires a T-1-type response to such synthetic antigens. We report that T-1-type (generating high CTL, low antibody) or T-2-type (the reciprocal) responses can be induced by conjugation of the antigen to the carbohydrate polymer mannan: T-1 responses are selected by using oxidizing conditions; T-2 responses are selected by using reducing conditions for the conjugation. Using human MUC1 as a model antigen in mice, immunization with oxidized mannan-MUC1 fusion protein (ox-M-FP) led to complete tumor protection (challenge up to 5 x 10(7) MUC1(+) tumor cells), CTLs, and a high CTL precursor (CTLp) frequency (1/6900), whereas immunization with reduced mannan-MUC1 FP (red-M-FP) led to poor protection after challenge with only 10(6) MUC1(+) tumor cells, no CTLs, and a low CTLp frequency (1/87,800). Ox-M-FP selects for a T-1 response (mediated here by CD8(+) cells) with high interferon gamma (IFN-gamma) secretion, no interleukin 4 (IL-4), and a predominant IgG2a antibody response; red-M-FP selects for a T-2-type response with IL-4 production and a high predominant IgG1 antibody response but no IFN-gamma.