Hydrogen peroxide in expired air condensate correlates positively with early steps of peripheral neutrophil activation in asthmatic patients.

We have found an increased H2O2 level in expired air of asthmatic patients. Neutrophils from these subjects generated higher amounts of superoxide radicals after challenge with phorbol esters than those from healthy subjects which may result from an increased activity of NADPH-oxidase. The enhanced Ca2+ mobilisation in neutrophils from asthmatics could be responsible for increased production and subsequent elevated H2O2 concentration in expired breath condensate. In this study we wished to determine whether neutrophils of asthmatic patients have enhanced [Ca2+]i response after N-formyl-methionyl-leucyl-phenylalanine--fMLP challenge as compared with cells from healthy donors, and if so, does it correlate with H2O2 levels in expired air. We examined 21 patients, 10 healthy individuals as a control group (mean age 34.3 +/- 5.5, 6 males and 4 females) and 11 asthmatic subjects (mean age 38.2 +/- 7.2, 7 males and 4 females). The rise of [Ca2+]i as an early event of neutrophil activation, was measured spectrofluorimetically with Fura-2-AM. The mean H2O2 level, measured spectrofluorimetrically in the expired breath of asthmatics, was 20-fold higher than that in healthy control (0.18 +/- 0.20 vs. 0.01 +/- 0.04 microM, p < 0.05). [Ca2+]i increase after challenge by fMLP (delta [Ca2+]i) was much higher in asthmatics than in control group (205.0 +/- 44 vs. 113.0 +/- 22 nM, p < 0.05, respectively). A strong correlation was observed between H2O2 and delta [Ca2+]i and maximal velocity of increase in [Ca2+]i in asthmatics (r = 0.87, p < 0.01 and r = 0.64, p < 0.05). We conclude that elevated H2O2 level in the expired breath condensate of asthmatics can be generated by activated neutrophils in the course of mucosal inflammation observed in bronchial asthma.