Inducible expression of granulocyte-macrophage colony-stimulating factor, tumor necrosis factor-alpha, and interferon-gamma in two human cytotoxic leukemic T-cell lines.

We investigated the ability of the TALL-103/2 and TALL-104 leukemic cell lines to produce lymphokines in response to activation signals, such as tumor cells and anti-CD3 (OKT3) or -CD2 (B67.1) monoclonal antibodies (mAb) or both. Both cell lines were found to produce high levels of interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and granulocyte-macrophage colony-stimulating factor (GM-CSF). The latter lymphokine is induced by lysable tumor cells and by immobilized OKT3 and B67.1 mAb only in the presence of interleukin (IL-2). IFN-gamma and TNF-alpha are induced upon CD3 but not CD2 stimulation, both in the presence and absence of IL-2. Interestingly, the B67.1 mAb amplifies the OKT3-induced responses by 2- to 10-fold, bringing the IFN-gamma and TNF-alpha levels of production up to 200 U/ml. Thus, simultaneous triggering of the CD2 and CD3 signaling pathways results in a very efficient lymphokine release. Of all the tumor cell lines tested as inducers, only K562 cells are able to stimulate the production of IFN-gamma and TNF-alpha in TALL-103/2 and TALL-104 cells, especially upon culture in IL-2. Lymphokine mRNA expression after stimulation with mAb or K562 cells peaks at 2 h in both cell lines. No messages are detectable in TALL-103/2 cells at 8 h, whereas in TALL-104 cells, IFN-gamma and GM-CSF transcripts are still present at 8 and 20 h, respectively. The inducible and highly regulatable expression of lymphokine release by these cell lines provides a unique model for studying mechanisms of lymphokine induction by different biological agents.