Cell interaction in tumor allograft immunity. Suppressor cell in the spleen of allogeneic tumor-sensitized mice.

The cytotoxic activity of lymphoid cells from allogeneic tumor-sensitized mice in three different strain combinations was tested at various intervals after i.p. sensitization. Peritoneal cells (PC) gave the highest cytotoxic index. The cytotoxic activity of the PC was due to both peritoneal lymphocytees (PL) and peritoneal macrophages (PM). Splenic macrophages, on the other hand, exerted an inhibitory effect as evidenced by increased cytotoxic activity of spleen treated with antimacrophages serum (AMS). Increased cytotoxic activity was also found in: (1) the nonadherent fraction of spleen after absorption on glass; (2) the effluent fraction of spleen after nylon wool column filtration; and (3) the medium density band after centrifugation of spleen on a discontinuous bovine serum albumin gradient. The results suggest the presence of an AMS-sensitive, glass- and nylon wool-adherent spleen cell which could have a suppressor role in allogeneic tumor-sensitized mice.