Lack of systemic oxidative stress during PAF challenge in mild asthma

To further establish the role of oxidative stress in the pathogenesis of acute bronchial asthma, we investigated the effects of platelet-activating factor (PAF) challenge on systemic oxidant-antioxidant balance in 12 asthmatic patients (age, 25+/-3[SEM] yr; FEV1, 95+/-10% predicted), using a double blinded, controlled with Lyso-PAF (L-PAF), cross-over design. Respiratory system resistance (Rrs), arterial blood gases, peripheral blood neutrophils and oxidant-antioxidant balance, including thiobarbituric acid (TBA)-malondialdehyde (MDA) adducts, protein sulphydryls and Trolox equivalent antioxidant capacity (TEAC), were assessed at baseline and 5, 15 and 45 min after PAF and L-PAF (18 microg each) bronchoprovocation. Urinary leukotriene E4 (uLTE4) elimination was measured 120 min after challenge. Compared with baseline, as expected, PAF increased significantly Rrs and AaPO2 and decreased PaO2 and peripheral blood neutrophils along with a rebound neutrophilia and increased uLTE4. By contrast, markers of systemic oxidative stress remained unaltered throughout the study. Unlike PAF, L-PAF-induced changes were negligible. We conclude that there is no systemic oxidant-antioxidant imbalance during acute bronchoconstriction induced by PAF in these patients with mild asthma.