DIFFERENT EFFECTS OF EXOGENOUS HORSERADISH-PEROXIDASE ON LUMINOL-AMPLIFIED CHEMILUMINESCENCE INDUCED BY SOLUBLE AND PARTICULATE STIMULI IN HUMAN NEUTROPHILS

The chemiluminescence (CL) technique with scavengers for superoxide an ion (superoxide dismutase) and hydrogen peroxide (catalase) was used t o characterize the generation of reactive oxygen species (ROS) inside and outside the human neutrophil after stimulation with both soluble ( formyl-methionyl-leucyl-phenylalanine. FMLP) and particulate (urate cr ystals, zymosan, oxidized LDL) stimuli. Depending on the stimulus used , ROS generation differed in composition and absolute amounts. The rat io between extracellularly and intracellularly produced ROS ranged fro m 0.3 (zymosan) to 4.2 (FMLP). While enhancing substantially FMLP-stim ulated CL, horseradish peroxidase inhibited CL induced by particulate stimuli by 40-80%. Furthermore, an azide-insensitive and therefore per oxidase-independent part of CL was found in FMLP-, LDL- and zymosan-st imulated cells. The results indicate that different agonists may lead through distinct chemical pathways to neutrophil luminol-amplified lig ht generation. (C) 1998 John Wiley & Sons, Ltd.