BACKGROUND: Benzo(a)pyrene (BP) is a known carcinogen and immunosuppressor.Activation of BP to its reactive intermediates is cyclo-oxygenase (COX) dependent and occurs via a freeradical dependent mechanism. The aim of this study was to know whether anti-oxidants, free radical quenchersand (COX) inhibitor, indomethacin, influence the suppression of human T cells induced by BP in vitro.MATERIAL/METHODS:Human lymphocytes, obtained from healthy human volunteers, were stimulated to proliferate using phytohaemagglutinin(PHA). The effect of vitamin E, SOD, catalase, mannitol, and COX-inhibitor, indomethacin, on BP-inducedsuppression of human T cell proliferation was evaluated.RESULTS: Except for catalase, a hydrogen peroxide(H2O2) radical quencher, none of the agents tested could inhibit BP-induced suppression of human T cellproliferation in vitro.CONCLUSIONS: BP-induced suppression of human T cell proliferation is probably,induced by increased production of H2O2. Prostaglandins and superoxide anion and hydroxyl radical donot seem to participate in BP-induced human T cell growth suppression.

Keywords: Benzo(a)pyrene, Cyclooxygenase Inhibitors, Free Radical Scavengers, Lymphocytes