Erythrocyte-mediated scavenging of reactive oxygen metabolites generated by human polymorphonuclear leukocytes during phagocytosis: comparison between normal and Down's syndrome blood cells.

The phagocytosis of complement-opsonized yeast particles by polymorphonuclear leukocytes from normal and Down's syndrome subjects was compared in the absence and presence of erythrocytes. Granulocytes from children with Down's syndrome showed a large increase of metabolic activity, as measured with chemiluminescence. This was not associated with autooxidative damage in the presence of erythrocytes. The results indicate that erythrocytes could exert an antioxidant effect on the granulocyte cell surface. This was reflected in an enhanced ingestion, which was more pronounced in the presence of Down erythrocytes with a higher superoxide dismutase and glutathione peroxidase content, than normal cells. Our conclusion is that the increase of reactive oxygen metabolites scavengers in Down's syndrome blood cells is of benefit for the homeostasis between generated reactive oxygen metabolites and their propagation.