RESUMO
The activity of peripheral phagocytes to generate reactive oxygen species (ROS) was studied in healthy individuals and patients with ischaemic stroke. The aim was to clarify the relationship between phagocyte activity, the time elapsed after the onset of disease and stroke severity. The total and extracellular production of ROS were evaluated by luminol chemiluminescence. Simultaneously the plasma oxidant activity was determined. When stimulated by opsonized zymosan, phagocytes in patients with stroke (regardless of its severity) showed fast activation. The total ROS generation increased over time in all stroke cases studied. However, the extracellular ROS generation was found to be greater in patients with severe stroke than in those with mild neurological deficiency. When stimulated by formyl-methionyl-leucyl-phenylalanine, the total oxidative phagocyte capacity (regardless of stroke severity) increased over time, but there was no change in the amount of extracellularly generated ROS. In patients with stroke the oxidant activity of plasma was enhanced. We conclude that circulating phagocytes in patients with ischaemic stroke are primed for enhanced ROS production by opsonin receptor-mediated stimulation and for increased secretion of myeloperoxidase by opsonin receptor-independent stimulation. The enhanced extracellular generation of ROS through opsonin receptor-dependent stimulation may be considered an oxidative stress biomarker in cerebral ischaemia.
