[Mechanisms of action of levamisole, stimulating cellular immune responses].

Since LMS possesses a thiazole and an imidazole (IMZ) moiety, we compared in vivo activities of LMS and of IMZ on immune responses of mice, IMZ was unable to increase the number of direct or indirect plaque-forming spleen cells to sheep red blood cells (SRBC), the magnitude of delayed hypersensitivity to SRBC, and did not evoke the production of a serum factor which passively transferred the immune stimulation. LMS was repeatedly active in these three tests. In vivo activities of LMS appear to be linked to its sulphur moiety able to recruit and activate a new population of T cells, through serum mediators.