Comparison between NO production in unstimulated PMN and LTC₄, LTD₄, LTB₄, or fMLP (all agonists were used at 100 nmol/L) stimulated PMN, assessed with the HbO₂ method as described in Materials and Methods. * .01 < P < .05; ** .005 < P < .01; *** P < .005 versus unstimulated PMN; mean ± SEM; n = 4.