Brief Communication: Induction of Macrophage-Mediated Tumor-Cell Cytotoxicity by Pyran Copolymer2

Abstract

Peritoneal macrophages taken from C57BL/6 mice inoculated with pyran (Hercules XA124-177) intraperitoneally were cytotoxic to tumor cells in vitro; normal macrophages had no effect. Macrophages harvested from mice 1 day after inoculation of pyran had no cytotoxic capacity; minimal macrophage cytotoxicity was present 3 days after pyran treatment; activity was maximal at 5 and 7 days after inoculation with pyran and had decreased by 11 days after drug administration. During the in vitro incubation, macrophage cytotoxicity was largely tumor specific; however, some cytotoxicity for normal cells was detected. Supernatants from pyran-activated or normal macrophages were not cytotoxic to tumor cells. Moreover, activated macrophages could be recovered from thymectomized, irradiated, bone marrow-reconstituted mice inoculated with pyran.