Enhanced in vivo sensitivity of in vitro interferon-treated B16 melanoma cells to CD8 cells and activated macrophages.
Mouse B16 melanoma cells maintained in vitro in the presence of interferon (IFN)-alpha become resistant to the in vitro antiproliferative effects of IFN-alpha. However, IFN-alpha-treated mice inoculated with these in vitro IFN-treated cells (B16 alpha res cells) have significantly increased life spans (ILS) and significantly higher cure rates than IFN-alpha-treated mice inoculated with B16 cells. This unexpectedly greater sensitivity of B16 alpha res cells to the in vivo antitumor effects of IFN-alpha was evaluated by in vivo cell depletion experiments. Depletion of either activated peritoneal macrophages or cytotoxic T lymphocytes (CTL) reduced the ILS of IFN-treated B16 alpha res-inoculated mice to a level comparable to that of IFN-treated B16-inoculated mice. Depletion of natural killer (NK) cells did not affect the ILS for IFN-treated B16 alpha res-inoculated mice. These studies indicate that activated macrophage and CD8 cell function, but not NK cell function, is important for the enhanced antitumor effects induced by IFN-alpha against B16 alpha res cells. Macrophage killing was unlikely to be mediated by TNF-alpha or IL-1 as B16 and B16 alpha res cells were equally sensitive to TNF-alpha and insensitive to IL-1 in vitro. Further, H-2K antigen expression is significantly more readily inducible on B16 alpha res cells than on B16 cells, consistent with enhanced CD8-mediated killing due to increased MHC class I antigen expression.
Fleischmann
C M
CM
Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston 77555, USA.
Stanton
G J
GJ
Fleischmann
W R
WR
D000704:Analysis of Variance; D000818:Animals; D000951:Antigens, Neoplasm / Q000187:drug effects; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D005069:Evaluation Studies as Topic; D005260:Female; D006183:H-2 Antigens / Q000187:drug effects; D007370:Interferon Type I / Q000627:therapeutic use*; D007694:Killer Cells, Natural / Q000276:immunology; D008262:Macrophage Activation / Q000276:immunology*; D017737:Macrophages, Peritoneal / Q000276:immunology*; D008546:Melanoma, Experimental / Q000188:drug therapy* / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D011994:Recombinant Proteins; D015996:Survival Rate; D014407:Tumor Cells, Cultured
D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D006183:H-2 Antigens; C032876:H-2Kb protein, mouse; D007370:Interferon Type I; D011994:Recombinant Proteins