text: Effects of prostaglandin E2 on Th0-type human T cell clones: modulation of functions of nuclear proteins involved in cytokine production. 
  The effects of prostaglandin E2 (PGE2) on cytokine production and proliferation of the CD4+ human helper T cell clone SP-B21 were investigated. In cells stimulated with anti-CD3 mAb, PGE2 inhibited cell proliferation and the production of all the cytokines examined. Addition of rIL-2 fully restored the proliferative response and partially restored the production of IL-4 and IL-5, but not that of other cytokines. In contrast, in cells stimulated with phorbol myristate acetate (PMA)/A23187, PGE2 enhanced the production of IL-4 and IL-5, and only partially inhibited the production of other cytokines. Therefore, the effects of PGE2 vary depending on the mode of T cell activation, and the IL-4 and IL-5 are regulated differently from other cytokines. In a mobility shift assay, only the NF-kappa B (p50/p50) homodimer was observed in a complex formed with the kappa B sequence in unstimulated SP-B21 cells. When cells were stimulated with anti-CD3 mAb or PMA/A23187, a complex formation of NF-kappa B (p50/p65) heterodimer with the kappa B sequence was induced. Interestingly, PGE2 or di-butyryl (Bt2)cAMP abolished the binding of NF-kappa B (p50/p65) heterodimer to the kappa B sequence in cells stimulated with anti-CD3 mAb but not with PMA/A23187. Our results suggest that the target of PGE2 action is a component in the signal transduction pathway leading to the activation of protein kinase C. However, the inhibition of the T cell activation signals by PGE2 is selective. PGE2 enhanced the complex formation with NF-AT, AP-1 and CLE0 sequences when the cells were activated by either anti-CD3 mAb or PMA/A23187 stimulation. It seems therefore that PGE2, by elevating cAMP levels, interferes with the activation pathway for NF-kappa B but not for NF-AT, AP-1 or CLE0 binding protein. 