Lipoxygenase inhibitors suppress IL-2 synthesis: relationship with rise of [Ca++]i and the events dependent on protein kinase C activation.

The present study was performed in an attempt to understand the mechanism involved in the inhibition of interleukin 2 (IL-2) synthesis by lipoxygenase (LO) pathway inhibitors. Using the two IL-2-producing lymphoid cell lines, (Jurkat and EL4 cells), we showed first that the inhibitory effect of the phenolic compounds tested (NDGA, BHA and caffeic acid) acted on lymphoid cells themselves and not on eventual monocytic or granulocytic contaminant cells. Secondly, these inhibitors were demonstrated as exerting their effect on two levels: they affected the events controlled by both second messengers implicated in T cell activation, namely rise of intracellular free calcium concentration [( Ca++]i) and protein kinase C (PKC) activation. For this purpose, LO inhibitor effects have been compared: (a) on IL-2 production by the two different lines: Jurkat cells, which need both signals, and EL4 cells, which require only PKC activation for the induction of this production; and (b) on the events induced by the different ways of Jurkat cell activation: PHA (or anti-CD3 monoclonal antibody) versus calcium ionophore. These results are discussed with respect to an eventual involvement of arachidonic acid [AA] derivatives in IL-2 synthesis.