Studies on antitumor activity of prumycin. IV. Effect of prumycin on mouse immune system.

The effect of prumycin on the mouse immune system was studied. Prumycin at a dose of 75 mg/kg (1/2LD50) showed essentially no suppression of hemolytic plaque forming cells (PFC) against sheep red blood cells (SRBC) when it was administered on day 0, 1 or 2. However, a weak suppression was observed by administration of prumycin on day 3. Also a remarkable suppression of PFC was demonstrated when mouse spleen cells were pre-incubated with prumycin at the concentration over 62.5 mg/kg in vitro. The delayed-type hypersensitivity reaction against SRBC was remarkably suppressed by cyclophosphamide, but it was not much by prumycin, except by administration on the day of elicitation. Prumycin of a high concentration inhibited an uptake of 3H-thymidine by mouse spleen lymphocytes incubated with or without phytohemagglutinin, but that of a low concentration, 1.9 approximately 0.03 mcg/ml, slightly increased the blastogenic stimulation of lymphocytes.