CAMP UP-REGULATES IL-4 AND IL-5 PRODUCTION FROM ACTIVATED CD4-CELLS WHILE DECREASING IL-2 RELEASE AND NF-AT INDUCTION( T)

Seven days after activation with concanavalin A and irradiated spleen cells, murine CD4(+) T cells were re-stimulated with ionomycin and pho rbol 12-myristate 13-acetate (PMA). IL-2 and IL-4 were determined in t he supernatant. When cholera toxin, forskolin together with phosphodie sterase inhibitors or dibutyryl-cAMP were added at the time of re-stim ulation, a dose-dependent increase of IL-4 and IL-5 release was noted. IL-2 was down-regulated as reported before. The up-regulation of IL-4 and the down-regulation of IL-2 correlated with an increase of IL-4 m RNA and a decrease of IL-2 mRNA as determined by semi-quantitative rev erse transcriptase polymerase chain reaction. Similar results were fou nd with prostaglandin E(2) using PMA and ionomycin or plate-bound anti -CD3 antibody as re-stimulants. These results suggest that, in activat ed CD4(+) T cells, cAMP-elevating agents induce a switch of lymphokine production towards a T(h)2-like phenotype through regulation at the t ranscriptional level. This is supported by the fact that complex forma tion between a synthetic nuclear factor of activated T cells (NF-AT) b inding site from the IL-2 promoter and nuclear extracts was decreased when cholera toxin was added to re-activated CD4(+) T cells, suggestin g that cholera toxin and cAMP down-regulate IL-2 expression via decrea sed NF-AT binding. Finally, since IL-4 has been reported to amplify IL -4 release from activated CD4(+) T cells, the autoinduction of IL-4 ma y very well function via cAMP.