MYELOPEROXIDASE-BASED CHEMILUMINESCENCE OF POLYMORPHONUCLEAR LEUKOCYTES AND MONOCYTES

Luminol and lucigenin chemiluminescence (CL) responses produced by sep arated human blood polymorphonuclear leukocytes (pmn) and monocytes (m ono) have been studied following stimulation with the surface-receptor agonist fMLP (a synthetic chemotactic peptide) and the protein kinase C activator phorbol myristate acetate (PMA). Pmn produced two- to thr eefold the luminol CL and superoxide anion (O-2(-)) levels of mono; lu cigenin CL was similar for both cell-types. The myeloperoxidaae (MPO) inhibitor salicylhydroxamic acid (SHA) abrogated luminol but not lucig enin CL in both cell types, but did not further inhibit the already gr ossly subnormal luminol CL responses seen with MPO-deficient cells whi ch produced normal lucigenin CL. SHA also profoundly inhibited the lum inol CL response in a cell-free MPO-H2O2 system. Mono lucigenin CL doe s not appear to specifically measure O-2(-) production. These data sho w that luminol CL provides a useful measure of pmn and also mono MPO a ctivity. However, analysis of the effects of various reactive oxygen s pecies (ROS) scavengers, assessed on phagocyte and cell-free CL system s (both MPO-H2O2 and superoxide generating) suggest that the luminol C L signal is not entirely dependent on MPO activity.