Regulation of the T 15 idiotype-positive, T-independent immune response to Streptococcus pneumoniae R 36 a (Pn). I. Specific suppressor T cells induced by Pn in vitro are antigen-specific and idiotype-positive.

Normal BALB/c spleen cells incubated for 2 days with Streptococcus pneumoniae R 36 a (Pn) vaccine in vitro acquired the specific ability to inhibit the T-independent anti-Pn response of fresh lymphocytes. The activated suppressor cells were susceptible to cytotoxic treatment with mouse anti-theta serum plus complement, and they inhibited the anti-Pn response of B lymphocytes deprived of T cells. The suppressive effect was eliminated by adsorbtion of cells on dishes coated with the C polysaccharide from Pn, and treatment of the suppressor cells with a rabbit antibody specific for TEPC-15 myeloma protein, in the presence of complement, abolished the suppressive effect. The results indicate that stimulation of lymphocytes with a T-independent antigen in vitro activates suppressor T cells bearing a specific antigen receptor that may express the idiotype(s) characteristic of anti-Pn antibody, and that these cells inhibit the Pn-reactive B cells directly.