When spleen cells are cultured for 4 days in the presence of fetal bovine serum, T-cells are generated which nonspecifically suppress the humoral responses of non-precultured cells to a variety of antigens. These T cells can be generated from both short-lived, sessile T1 cells and long-lived, recirculating T2 cells, and thus appear similar to suppressor T cells activated by concanavalin A.