Interferon-gamma enhances induction of lymphotoxin in recombinant interleukin 2-stimulated peripheral blood mononuclear cells.

Human peripheral blood mononuclear cells (PBMC) were induced by recombinant human interleukin 2 (rIL 2) to secrete lymphotoxin (LT) and interferon-gamma (IFN-gamma). Induction of both LT and IFN-gamma by rIL 2 is regulated at the transcriptional level. Treatment of PBMC with rIL 2 in combination with recombinant human IFN-gamma (rIFN-gamma) resulted in an earlier appearance of LT mRNA and an augmented production of LT than did rIL 2 treatment alone. IFN-gamma alone had no effect on production of either LT or its mRNA. PBMC cultured in the presence of rIL 2 plus anti-rIFN-gamma resulted in decreased LT production. Only a 15-min incubation of PBMC with rIL 2 is needed to stimulate LT production, whereas 3 hr is necessary for IFN-gamma production. These results suggest that rIL 2, in addition to being a T cell growth factor, may exhibit other activities through induction of LT and IFN-gamma.