Interleukin-2 Production by T Cells: A Study of the Immunoregulatory Actions of Interferon-α, Interferon-γ, and Tumor Necrosis Factor-α in Phenotypically Different T Cell Clones

The production of interleukin 2 (IL-2) by phytohemagglutinin (PHA)-stimulated human leukemia T cell lines MOLT-13 and MOLT-14, the T cell receptor (TcR) γδ-bearing clones, was significantly increased by adding human natural interferon-γ (IFN-γ) to the cell cultures. In addition, the IL-2 production by PHA-stimulated MOLT-13 and MOLT-14 cells was also augmented by human natural tumor necrosis factor-α (TNF-α) in a dose-dependent manner but was inhibited by IFN-α even at low concentrations (10 IU/ml). This pattern of reactivity is different from the responsiveness of the MOLT-16 cells, a TcR αβ-bearing cell line, which respond to IFN-α and TNF-α, but not to IFN-γ, by augmentation of IL-2 production. These results suggest that (1) the addition of IFN-γ has a direct effect on PHA-stimulated MOLT-13 and MOLT-14, resulting in an augmentation of IL-2 production; (2) phenotypically different T cell lines vary in their susceptibility to IFN-α and IFN-γ regulation; and (3) the augmentation of IL-2 production by TNF-α appears to have no correlation with phenotypically different T cell clones.