Enhancement of immune responses and possible inhibition of suppressor cells by aclacinomycin A.

Antitumor antibiotics were examined as possible candidates that possess activity which inhibits preferentially suppressor cells in comparison with effector cells. In screening for such compounds among known antibiotics, aclacinomycin was found to augment antibody formation and delayed-type hypersensitivity in mice over a wide concentration range. The addition of aclacinomycin to mouse spleen cell cultures also enhanced antibody formation in vitro. The generation of suppressor cells or the suppressor activity per se in mice immunized with high doses of SRBC was reduced by aclacinomycin. These results suggest that the drug may possibly inhibit suppressor cells selectively. The administration of aclacinomycin at ow doses exhibited antitumor effects on IMC carcinoma; the effect was not dose-dependent.