title: Enhanced susceptibility of target KMT-17 cells to activated macrophages by treatment with the antitumor agent bleomycin.
abstract: We observed that after KMT-17 cells had been treated with bleomycin (BLM), even with a dose as high as 160 micrograms/ml, they were still able to form colonies in soft agar. We then studied the susceptibility of KMT-17 cells treated with BLM to activated macrophages. During a colony inhibition assay, BLM-treated KMT-17 cells were found to be much more susceptible to activated macrophages than nontreated KMT-17 cells, moreover, a tumor neutralizing assay showed that the growth of BLM-treated KMT-17 cells was also significantly inhibited by activated macrophages as compared with nontreated KMT-17 cells. Macrophages activated by both BLM and the Nocardia rubra cell wall skeleton were able to mediate such tumor inhibition activity in BLM-treated KMT-17 cells. Activated macrophages did not seem to have strong antitumor activity against nontreated KMT-17 cells in vivo, however, the life span of the rats which were inoculated i.p. with KMT-17 cells was significantly expanded after the tumor-bearing rats were given BLM i.p. The data presented here suggest that not only does BLM have a direct tumoricidal effect on KMT-17 cells, it also regulates immunosensitivity of targets to immune effectors. We also discuss the mechanism for enhancing the susceptibility of KMT-17 cells to activated macrophages brought about by treatment with BLM.
mesh_terms: D000818:Animals; D001761:Bleomycin / Q000008:administration & dosage / Q000627:therapeutic use*; D002460:Cell Line; D002470:Cell Survival; D007274:Injections, Intraperitoneal; D008262:Macrophage Activation; D008264:Macrophages / Q000187:drug effects / Q000276:immunology*; D009374:Neoplasms, Experimental / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D010529:Peritoneal Cavity / Q000166:cytology; D051381:Rats; D014410:Tumor Stem Cell Assay
chemical_list: D001761:Bleomycin