Hydrogen peroxide (H2O2) production in exhaled air was measured in ventilated preterm newborns at 5, 24 and 48 hours after delivery, using originally designed method of exhaled breath condensate (EBC) collection. H2O2 production in expired gas was 812±34 pmol/20 min during the first measurement and then declined to 389±21 at 24 hours and 259±26 pmol/20 min at 48 hours.
Phagocytosis is associated with respiratory burst producing reactive oxygen and nitrogen species. Several studies imply that erythrocytes can inhibit the respiratory burst during erythrophagocytosis. In this work we studied the mechanisms of this effect using control and in vitro peroxidized erythrocyte membranes. We demonstrated that autofluorescence of peroxidation products can be used for visualization of phagocytozed membranes by fluorescence microscopy. We also found that respiratory burst induced by a phorbol ester was inhibited by control membranes (5 mg/ml) to 63 % (P0.001), and to 40 % by peroxidized membranes (P0.001). We proved that this effect is not caused by the direct interaction of membranes with free radicals or by the interference with luminol chemiluminescence used for the detection of respiratory burst. There are indications of the inhibitory effects of iron ions and free radical products. Macrophages containing ingested erythrocyte membranes do not contain protein-bound nitrotyrosine. These observations imply a specific mechanism of erythrocyte phagocytosis.