Tolerogen‐Mediated Suppression of the Immune Response: Suppressor Cells as Passive Transfer Agents

The anti‐dinitro‐phenyl (Dnp)IgM antibody response in mice was inhibited by administration of either a non‐immunogenic form of Dnp‐polyacrylamide (Dnp‐Pa) or an excess amount of an immunogenic form of Dnp–Pa. Spleen cells, alive or heat‐killed, from mice tolerized in vivo by either method, inhibited the anti‐Dnp response of naive spleen cells co‐cultured in vitro with antigen. Conversely, donor cells tolerized in vivo by a high dose of immunogenic Dnp–Pa, when titrated into a naive cell culture which contained no antigen, produced a stimulatory dose‐response curve. Both the dose‐dependent inhibition and stimulation correlated strongly with the amount of ¹²⁵I‐labelled Dnp–Pa carried over by tolerized spleen cells into the naive cell culture system. Because the doses and experimental procedures used were comparable to those commonly used for suppressor cell generation and assay, it is suggested that antigen‐specific suppressor cells may produce their effects through passive transfer of antigen and/or tolerogen.