Factors affecting the cytokine production of human T cells stimulated by different modes of activation.

According to the widely accepted classification, human TH cell clones can be divided into two mutually exclusive subsets, TH1 and TH2, based on their profile of cytokine production. The intracellular difference between these clones is not clear. To characterize the biochemical nature of T-cell receptor (TCR)/CD3 complex-mediated signal transduction pathways, we introduced several human TH cell clones of THO- or TH1-like phenotype and analyzed the effects of various drugs and antibodies on cytokine production or proliferation of these clones. The tyrosine kinase inhibitor herbimycin inhibited the production of interferon-gamma (IFN-gamma) by THO-like clone, after stimulation with anti-CD3 monoclonal antibody alpha CD3-mAb) or with phorbol 12-myristate 13-acetate (PMA) and the calcium ionophore A23187. However, whereas herbimycin strongly inhibited the production of IL-4 and IL-5 by alpha CD3 mAb stimulated T cells, it did not affect the production of these cytokines after PMA/A23187 stimulation. Cyclosporin A inhibited the proliferation as well as the production of the cytokines, including that of IL-2, IL-4, IL-5, and IFN-gamma, irrespective of the mode of stimulation. A23187, which synergizes with PMA in the induction of IL-4 and IFN-gamma, inhibited PMA-induced IL-10 production in a dose-dependent manner. Transforming growth factor-beta and anti-IL-2 receptor monoclonal antibody partially inhibited alpha CD3 mAb-mediated T-cell proliferation, but had no effect on the proliferation induced by PMA and A23187. Cyclic adenosine monophosphate (cAMP)-elevating drugs, like prostaglandin E2 and dibutyryl cAMP, inhibited the TCR-mediated cytokine production but shifted the cytokine production profile from a TH0 to a TH2 type after stimulation with PMA and A23187. Finally, we analyzed the induction of activity of two transcription factors, nuclear factor-kappa B (NF-kappa B) and nuclear factor of activated T cells, involved in the regulation of cytokine gene expression, after a different mode of activation. The induction of NF-kappa B (p50/p65 heterodimer) by using alpha CD3-mAb stimulation but not by using PMA/A23187 stimulation was found to be inhibited by using cAMP-elevating drugs.