In vivo antitumor mechanism of natural human tumor necrosis factor involving a T cell-mediated immunological route.

We have investigated the in vivo antitumor mechanism of natural human tumor necrosis factor (n-TNF) isolated from a culture of human leukemic B cell line (BALL-1), especially its action as an immunomodulator, and found that the in vivo antitumor effect of n-TNF on Meth A sarcoma implanted in BALB/c mice pretreated with monoclonal antibody against T cell-specific surface antigen (Thy-1) was significantly diminished. Furthermore, when BALB/c mice were treated with T cell subset-specific monoclonal antibodies, anti-L3T4 or anti-Lyt-2.2, the antitumor effect of n-TNF on Meth A sarcoma was significantly reduced. Therefore, it was suggested that the in vivo antitumor mechanism of n-TNF might involve a T cell-mediated immunological route.