Scavengers of reactive oxygen intermediates do not mediate the depression of macrophage hydrogen peroxide production caused by erythrocyte phagocytosis

Abstract

Our previous studies have shown that a phagocytic challenge with IgG-coated erythrocytes (EIgG) depressed macrophage triggered H2O2 production in vitro, and in vivo there was a decrease in the survival rate following bacteremia. The phagocytosis of an equal number of IgG-coated erythrocyte ghosts had none of these effects, indicating that the contents of the erythrocytes are important for these effects. The present study evaluated the role of the scavengers of reactive oxygen intermediates within erythrocytes in the depression of H2O2 production triggered with phorbol myristate acetate following a phagocytic challenge with EIgG. Elicited rat peritoneal macrophages (PM) were challenged with EIgG prepared from normal E or E with inactivated catalase, depleted glutathione, hemoglobin converted to methemoglobin, or fixed with formaldehyde. The depression of triggered H2O2 production was similar when equal numbers of normal EIgG and EIgG with inactivated scavengers were phagocytized. When the phagocytic challenge with normal EIgG was carried out in the presence of cytochalasin B, no depression of triggered H2O2 production was observed. Cytochalasin B partially blocked the phagocytosis of EIgG, so that with larger doses of EIgG there was sufficient ingestion of EIgG to depress H2O2 production in untreated PM. These results indicate that the scavengers of reactive oxygen intermediates present in erythrocytes are neither required nor sufficient to depress H2O2 production by macrophages.