Stimulation of antibody synthesizing lymphocytes in the rat by antigen reactive cells sensitized in vitro.

Lymphocytes obtained from rat spleens were sensitized in vitro to sheep erythrocytes. The sensitized lymphocytes did not synthesize antibody but when injected into unimmunized rats did stimulate antibody production to sheep erythrocytes. Analysis of the location of 7 and 19 S plaque-forming cells in the recipient rats indicated that these two antibody synthesizing cell populations arise from different lymphocytes. It was also found that the sensitized lymphocytes could react only with a limited number of antibody synthesizing cells.