Aclacinomycin inhibits suppressor cells in vivo and in vitro.

After the intraperitoneal injection of aclacinomycin into mice, a variety of immune responses are increased. The responsible mechanism is the elimination of suppressor cells since aclacinomycin inhibits the expression of tolerance to SRBC in mice and diminishes the capacity of spleen cells from SRBC-tolerant mice to inhibit the response of normal animals upon adoptive transfer, either when injected to the donor tolerant mice before the cell transfer or when in vitro incubated with the tolerant cells for 1 hour: both treatments had eliminated suppressor cells from the tolerant spleen cell population.