Suppressive effects of a novel antioxidant compound on human T cell functions in vitro.

The use of antioxidant compounds with differing modes of action has clearly demonstrated involvement of oxidative processes in the activation of T lymphocytes. In this paper, we show that a novel antioxidant (lazaroid U75412E, a free radical scavenger) suppressed mitogen-induced T cell proliferation in vitro. Similar results were obtained with diphenylene iodonium (DPI), a known inhibitor of NADPH oxidase. The lazaroid was further shown to inhibit IL 2 production but to be less potent in suppressing IL 2 receptor expression. Thus, scavenger-type antioxidants act on T cells primarily by blocking a signal necessary for the induction of IL 2 synthesis such as the activation of NF kappa B. Furthermore, the potent inhibition of lymphocyte responses caused by the specific enzyme inhibitor DPI provides direct proof of the source of the oxidants involved in these processes.