Regulation of the in vitro concanavalin A response of lymphocytes by cyclophosphamide-sensitive adherent cells--a possible role of Cy-sensitive regulatory cells.

On days 1--6 after cyclophosphamide (Cy) treatment, when a decrease in the number of spleen cells is observed, the stimulation of these cells by low doses of concanavalin A (ConA) is suppressed, but the response to high doses of this mitogen is enhanced. Removal of glass wool-adherent cells produces a similar bidirectional effect on the ConA dose-response; this effect is reversed upon reconstitution of these cells. Selective removal of macrophages by carrageenan does not produce this effect. Therefore, out data indicate that the primary Cy-sensitive targets are positive and negative regulatory cells, i.e. glass wool-adherent splenic cells, but are probably not macrophages.