title: Antitumor effects of interferon in mice injected with interferon-sensitive and interferon-resistant Friend leukemia cells. II. Role of host mechanisms.
abstract: We have attempted to determine what host mechanisms are responsible for inducing a rapid decrease in the number of Friend leukemia cells (FLC) in the peritoneal cavity of interferon-treated mice. By injecting radiolabelled FLC, we showed that there was a greater loss of radioactivity from individual interferon-treated mice than from control mice. Thus, it was likely that fewer cells were recovered from the peritoneal cavity of interferon-treated mice because of cell destruction. Treatment of mice with interferon limited to the period preceding tumor-cell inoculation conferred some degree of antitumor activity, although this regimen was far less effective than when interferon treatment was initiated and continued daily after tumor-cell inoculation. We have been unable to transfer any antitumor activity with peritoneal washings containing macrophages and lymphocytes from interferon-treated donor mice to tumor-inoculated recipient mice. Inoculation of silica particles i.p., which destroys macrophage function and may affect NK cell activity, did not abrogate interferon's antitumor activity. We suggest that interferon induces a host-mediated antitumor effect by mechanisms which are not mediated by easily recoverable soluble factors or by cytotoxic cells. The nature of this potent interferon-induced host mechanism remains unknown.
mesh_terms: D000818:Animals; D001202:Ascitic Fluid / Q000166:cytology; D005260:Female; D005622:Friend murine leukemia virus; D007372:Interferons / Q000008:administration & dosage / Q000494:pharmacology*; D007942:Leukemia, Experimental / Q000276:immunology / Q000628:therapy*; D008214:Lymphocytes / Q000276:immunology; D008264:Macrophages / Q000276:immunology; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D012822:Silicon Dioxide / Q000494:pharmacology; D013997:Time Factors; D014412:Tumor Virus Infections / Q000276:immunology / Q000628:therapy
chemical_list: D012822:Silicon Dioxide; D007372:Interferons