Production of reactive oxygen species and chemiluminescence by human monocytes during differentiation and lymphokine activation in vitro.

The zymosan-induced respiratory burst of human monocytes was studied, measuring the generation of reactive oxygen species (ROS) and luminol-dependent chemiluminescence (CL). The monocytes' ability to generate ROS declined markedly during the first 24 hours of culture, but regained the original level during the following three days. In contrast, the CL-response declined steadily during the same period. In vitro activation by lymphokines from lymphocytes stimulated with bacillus Calmette-Guérin gave a significant increase in ROS-generation; the CL-response was only marginally increased, but activated cells consistently displayed an altered kinetics of the CL-response with a more rapid decline from peak CL-values. These findings indicate that the production of ROS is not the limiting factor for the magnitude of the CL-response in the present experimental system and that the CL-assay may be an uncertain way of quantitating ROS.