Production of suppressor factor by T-cells from mice immunized with pneumococcal polysaccharide.

Factor(s) derived from plate purified T-cell cultures obtained from mice 16 hr after immunization with Type III pneumococcal polysaccharide (SSS-III), suppressed the antibody response to SSS-III. Such suppression was antigen specific. Adsorption of the suppressor factor (SF) with SSS-III covalently bound to Sepharose 4B column did not alter the ability of SF to suppress the antibody response. However, adsorption of SF with Ig+(B) cells taken from mice 48 hr after immunization with an immunogenic dose (0.5 ug) of SSS-III, completely removed the suppressive activity. Suppression of the antibody response was observed only when SF was administered 24 hr before to 24 hr after immunization with SSS-III. These results suggest that antigen specific suppressor T cells release soluble factor(s) which acts directly on antigen-stimulated B cells or may inhibit the induction of amplifier T-cells.