Contribution of nitric oxide synthase to human neutrophil chemiluminescence

A chemiluminescence (CL) assay has been used to measure the reactive oxygen species (ROS)-generating capacity of phagocytes. Primed neutrophils produc e ROS and nitric oxide (NO) upon induction of nitric oxide synthase (NOS) a ctivity. NO and superoxide (O-2(-)) form peroxynitrite (ONOO-), and emit CL . We examined the involvement of NOS in the CL response of neutrophils usin g a method based on the modulation of enzyme activity of NOS by the substra te L-arginine and an inhibitor; L-NAME. We used lipopolysaccharide (LPS) as the neutrophil-priming agent. Addition of sodium azide (NaN3) with horsera dish peroxidase (HRP) to luminol-dependent CL, gave a CL response that was significantly enhanced when 10 mmol/L L-arginine was present (p < 0.05), su ggesting that NOS activity contributed to the CL response of human neutroph ils. LPS-primed luminol-dependent CL was significantly inhibited by L-NAME compared with D-NAME. The proportion of the difference between the two inhi bitors in luminol-dependent CL was 12.3 +/- 15.0%. Therefore, approximately 12% of the LPS-primed luminol-dependent CL decrease induced by L-NAME indi cated the contribution of NOS activity to the CL response. Copyright (C) 19 99 John Wiley & Sons, Ltd.