FACTORS AFFECTING THE CYTOKINE PRODUCTION OF HUMAN T-CELLS STIMULATEDBY DIFFERENT MODES OF ACTIVATION

According to the widely accepted classification, human T-H cell clones can be divided into two mutually exclusive subsets, T-H1 and T-H2, ba sed on their profile of cytokine production. The intracellular differe nce between these clones is not clear. To characterize the biochemical nature of T-cell receptor (TCR)/CD3 complex-mediated signal transduct ion pathways, we introduced several human T-H cell clones of T-H0- or T-H1-like phenotype and analyzed the effects of various drugs and anti bodies on cytokine production or proliferation of these clones. The ty rosine kinase inhibitor herbimycin inhibited the production of interfe ron-gamma (IFN-gamma) by T-H0-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 herb imycin 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 cyt okines after PMA/A23187 stimulation. Cyclosporin A inhibited the proli feration 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 stimulat ion. A23187, which synergizes with PMA in the induction of IL-4 and IF N-gamma, inhibited PMA-induced IL-10 production in a dose-dependent ma nner. Transforming growth factor-beta and anti-IL-2 receptor monoclona l antibody partially inhibited alpha CD3 mAb-mediated T-cell prolifera tion, but has no effect on the proliferation induced by PMA and A23187 . Cyclic adenosine monophosphate (cAMP)-elevating drugs, like prostagl andin E(2) and dibutyryl cAMP, inhibited the TCR-mediated cytokine pro duction but shifted the cytokine production profile from a T-H0 to a T -H2 type after stimulation with PMA and A23187. Finally, we analyzed t he 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 u sing alpha CD3-mAb stimulation but not by using PMA/A23187 stimulation was found to be inhibited by using cAMP-elevating drugs.