title: Resistance of in vivo-selected spontaneously transformed cells and Rous sarcoma virus-transformed cells to macrophage-mediated cytotoxicity.
abstract: The cytotoxic activity (CTA) of activated peritoneal macrophages (MP) on variant lines of Syrian hamster embryo (HE) cells of differing malignant characteristics was studied. The target cells were a line of low-malignant cells resulting from spontaneous transformation of HE cells in vitro (STHE strain), and malignant variants selected from them in vivo (STHE-LM-4, STHE-LM-8, and STHE-75/18 strains). In addition, we used cells of the HET-SR-1 strain; these are HE cells transformed in vitro by a tumorigenic Rous sarcoma virus (Schmidt-Ruppin strain, RSV-SR), or the TU-SR strain induced by RSV-SR in vivo. Thioglycollate-elicited peritoneal MP from Syrian hamsters were activated in vitro with bacterial levan, LPS or MDP and used as effector cells. MP-mediated cytolysis was determined by means of a 42-h radioactivity release assay with 3H-thymidine-labeled target cells. We found that only the parental STHE cells were susceptible towards fully-activated MP-mediated CTA. All three of the in vivo-selected malignant variants of the STHE cell sublines, as well as the tumorigenic RSV-SR transformants, were resistant to cytolysis by activated MP. Non-activated thioglycollate-elicited MP did not lyse any of the tumor cells studied.
authors.affiliation: Laboratory of Anti-tumor Immunity, Academy of Medical Sciences, Moscow, Russia.
authors.forename: E A
authors.initials: EA
authors.lastname: Volpe
mesh_terms: D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000494:pharmacology; D000818:Animals; D001202:Ascitic Fluid / Q000166:cytology; D001358:Avian Sarcoma Viruses; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic; D002472:Cell Transformation, Viral; D006224:Cricetinae; D003602:Cytotoxicity, Immunologic; D004622:Embryo, Mammalian; D005630:Fructans / Q000494:pharmacology; D008070:Lipopolysaccharides; D008262:Macrophage Activation / Q000187:drug effects; D008264:Macrophages / Q000276:immunology*
chemical_list: D005630:Fructans; D008070:Lipopolysaccharides; D000119:Acetylmuramyl-Alanyl-Isoglutamine; C072599:levan