Enhanced production of IL-6 in tumor-bearing mice and determination of cells responsible for its augmented production.
IL-6 is a cytokine secreted in normal individuals by monocytes, fibroblasts, and endothelial cells. We have found increased levels of IL-6 in the sera from MH134 hepatoma- and CSA1M fibrosarcoma-bearing mice. Concerning the capacity of these tumor cells themselves to produce IL-6 in vitro, they exhibited the distinct contrast, i.e., the MH134 tumor cells produced high levels of IL-6 whereas the CSA1M generated a marginal level of IL-6. It was, however, demonstrated that appreciably enhanced IL-6 production was observed in spleen cell culture supernatants from both types of tumor-bearing mice when compared to those obtained from normal mice. More importantly, in contrast to the production of IL-6 by non-T cell compartment of normal spleen cells, enhanced IL-6 production of spleen cells from tumor-bearing mice was ascribed to T cell compartment. Analysis of T cell phenotype has revealed that enhanced IL-6 production was mediated predominantly by Lyt-2+ but not by L3T4+ T cell subset. Thus, these results indicate that increased circulating IL-6 is elicited in the tumor-bearing state and that irrespective of the potential of tumor cells themselves to produce IL-6, T cells, especially Lyt-2+ T cells from tumor-bearing mice are responsible for such a high level of IL-6 production.
Utsumi
K
K
Biomedical Research Center, Osaka University Medical School, Japan.
Takai
Y
Y
Tada
T
T
Ohzeki
S
S
Fujiwara
H
H
Hamaoka
T
T
D000818:Animals; D000950:Antigens, Ly / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis; D002469:Cell Separation; D007158:Immunologic Techniques; D015850:Interleukin-6 / Q000096:biosynthesis*; D008114:Liver Neoplasms, Experimental / Q000378:metabolism; D008213:Lymphocyte Activation; D051379:Mice; D008815:Mice, Inbred Strains; D009374:Neoplasms, Experimental / Q000378:metabolism*; D012513:Sarcoma, Experimental / Q000378:metabolism; D013154:Spleen / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism*; D018800:Thy-1 Antigens; D014407:Tumor Cells, Cultured
D000950:Antigens, Ly; D000954:Antigens, Surface; D015850:Interleukin-6; D018800:Thy-1 Antigens