Generation of Cytotoxic Factor by Human Large Granular Lymphocytes During Interaction With Autologous Tumor Cells: Lysis of Fresh Human Tumor Cells

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Abstract
Large granular lymphicytes (LGL) obtained by centrifugation (Percoll gradient) of blood from patients with carcinomatous pleural effusions and solid tumors lysed autologous, freshly isolated tumor cells in a 4-hour 5 Cr-release assy. When cocultured with autologous tumor Cells, LGL released souble cytotoxic factor(s), large granular lymphocyte-derived cytotoxic factor (LGL-CF). In contrast, small T lymphocytes were unable to kill autologous tumor cells or to produce a cytotoxic factor. The LGL-CF demonstrated cytotoxcity against autologous fresh tumor cells but also against allogeneic fresh tumor cells in a 48-hour microcytotoxicity assay and in an 18-hour 5Cr-release assay in the presence of dactionomycin. Binding of LGL-CF to autologous tumor cells occurred within 2 hours and reached the maximum by 6 hours; this binding was sufficient to cause subsequent lysis of the target cells without the continued presence of LGL-CF. Neither the supernatants produced by culture of LGL alone nor the lysates of LGL-CF. had detectable cytolytic activity. In addition, treatment of LGL with cytochalasin A inhibited both direct cell-mediated autologous tumor lysis and generation of LGL-CF. Production of LGL-CF required active cell metabolism and protein and RNA syntheses in LGL, but not DNA synthesis. Addition of dactinomycin to LGL-CF in assays augmented the lysis. LGL-GF was stable at 56° but it was reduced at 70 ° and destroyed at 100 ° Treatment of LGL-GF with trypsin or proteinase K reduced or abrogated the lytic effect, respectively, while the lytic effect was not affected by papain, catalase, or superoxide dismutase. These results indicate that during interaction with autologous tumor cells, LGL release a soluble cytotoxic factor that mediates lysis of fresh human tumor cells. [J Natl Cancer Inst 1988:80:1398–14030]

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