title: Effect of endotoxin on tumor resistance in mice.
abstract: As reported earlier, an intraperitoneal injection of 1 mug of endotoxin (ET) from Serratia marcescens rendered mice resistant against the nonspecific mouse ascites tumor TA3-Ha upon challenge 24 h after pretreatment with ET. Further studies were aimed at the elaboration of conditions which achieved maximal resistance. It appears that (i) a 10-mug dose of ET was approximately the optimal dose for protection; (ii) pretreatment with ET 3 to 0 days prior to tumor challenge gave best protection; and (iii) the intravenous injection of ET showed a lower protection against the tumor than intraperitoneal application. Studies on the mechanism of ET protection indicate that (i) ET does not have a direct cytotoxic effect on tumor cells; (ii) normal spleen cells exposed to ET in vitro can adoptively transfer protection against tumor; and (iii) spleen cells activated in vivo by intravenous injection of ET can adoptively transfer protection. The possible involvement of mononuclear cells is discussed.
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000276:immunology*; D002470:Cell Survival; D004305:Dose-Response Relationship, Drug; D004731:Endotoxins / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D007116:Immunization, Passive; D066298:In Vitro Techniques; D007274:Injections, Intraperitoneal; D007275:Injections, Intravenous; D008213:Lymphocyte Activation / Q000187:drug effects; D008214:Lymphocytes / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008974:Mollusca; D009368:Neoplasm Transplantation; D012706:Serratia marcescens / Q000276:immunology; D013154:Spleen / Q000166:cytology; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors; D014020:Tissue Extracts; D014316:Tritium
chemical_list: D004731:Endotoxins; D014020:Tissue Extracts; D014316:Tritium; D013936:Thymidine