Lymphokine production by human melanoma tumor-infiltrating lymphocytes

Summary

Lymphokine production by human melanoma tumor-infiltrating lymphocytes (TIL) was studied. Uncultured TIL produced interferon γ (IFNγ), but not interleukin-2 (IL-2) or IL-4, in response to anti-CD3 mAb or IL-2. In bulk cultures, IL-2-activated TIL displaying autologous tumor-specific cytotoxicity (CTL-TIL) produced IFNγ in culture with medium alone, whereas IL-2-activated noncytotoxic TIL did not. Addition of anti-CD3 mAb or autologous tumor cells up-regulated IFNγ production in IL-2-activated TIL from 10 of 12 or 6 of 12 cases respectively. Those from 4 of 12 cases (2 CTL-TIL and 2 noncytotoxic TIL) produced IL-2 in culture with medium alone. At the clonal level, 5 (4 CD4⁺ and 1 CD8⁺) of 7 autologous tumor-specific CTL clones derived from TIL and 3 (2 CD4⁺ and 1 CD8⁺) of 7 noncytotoxic TIL clones produced IFNγ in culture with medium alone, which was up-regulated by adding anti-CD3 mAb. Two IFNγ-producing CTL clones tested produced IL-2 in 4 ×-concentrated supernatants from a 3.5-h culture with medium alone. Furthermore, 2 IFNγ-producing CTL clones tested expressed mRNA for both IFNγ and IL-2. IL-2 production and its mRNA expression were up- or down-regulated, respectively, by adding anti-CD3 mAb or autologous tumor cells. IL-4 production was not observed in culture either with medium alone or with IL-2 in any of the cells described above. Anti-CD3 mAb was required for IL-4 production in 3 of 12 IL-2-activated TIL, 2 of 6 CTL clones, and none of 5 noncytotoxic TIL clones. In summary, IFNγ production was characteristic of melanoma TIL. Some autologous tumor-specific CTL in TIL are suggested to be productive of IL-2 and IFNγ under unstimulated conditions, both being required for self-activation in an autocrine loop.