[Anti-tumor effect of peritoneal exudate cells (macrophages) exposed to adriamycin]

The present study was undertaken to investigate antitumor activity of peritoneal exudate cells (PEC) collected from mice treated with adriamycin (ADM) intraperitoneally (ADM-PEC). PEC following intraperitoneal (i.p.) administration of 0.1, 1, and 10mg/kg of ADM exhibited in vitro antitumor activity against Ehrlich JTC-11 cells with dose-dependency. This activity was seen strongly in plastic adherent cells and was reduced by pretreatment with carrageenan. Therefore it was thought that effector cells were chiefly macrophages (M phi). In the supernatant of ADM-PEC obtained by ultrasonic disruption, ADM was released with dose-dependency. This supernatant inhibited proliferation of JTC-11 cells, but it was not cytocidal. ADM-PEC displayed pronounced antitumor activity in Winn assay. Fluorescent microscopy revealed that ADM-PEC contained yellow substances like ADM in the cytoplasma and that JTC-11 contained its yellow substances in the nuclear when JTC-11 had been incubated together with ADM-PEC. From these results, it was suggested that following i.p. administration ADM exhibited not only direct antitumor activity but also indirect antitumor activity by way of host immunity, namely through PEC, chiefly M phi, and this effect might be explained by transference of ADM, once phagocytized by M phi, into target cells.