Restoration by levamisole of immune responses suppressed in tumor-bearing mice.

Restorative effects of levamisole on suppressed immune responses were observed in BALB/c mice inoculated with a syngeneic methylcholanthrene-induced fibrosarcoma and immunized with nucleated chicken erythrocytes. In tumor-bearing mice, cell-mediated cytotoxicity, delayed footpad reaction, and antibodies were suppressed, and only the delayed footpad reaction was restored by levamisole. Suppressive effects in tumor-bearing mice can be transferred with sera or spleen cells, and the expression of suppressive effects cannot be abolished by treatment of the recipients with levamisole. However, the generation of suppressor mechanisms was affected by treatment of tumor-bearing donors with levamisole.