Antioxidants and Protein Carbonyls in Bronchoalveolar Lavage Fluid of Children: Normal Data

Antioxidant-oxidant imbalances in bronchoalveolar lavage fluid (BAL) are thought to contribute to oxidative stress in respiratory disease. However, normal reference ranges for BAL antioxidants and oxidized proteins in children are not available. In this study, we recruited 124 children attending for elective surgery for a noninflammatory condition; 83 were nonasthmatic, nonatopic (N) and 41 were nonasthmatic, atopic (NA). A nonbronchoscopic lavage was performed and ascorbate, uric acid, α-tocopherol, and protein carbonyl (as a measure of oxidative damage) concentrations were determined in BAL fluid. The 95% reference range was 0.112–1.897 μmol/L for ascorbate, 0.149–2.163 μmol/L for urate, 0.0029–0.066 μmol/L for α-tocopherol, and 0.280–4.529 nmol/mg for protein carbonyls in BAL fluid. Age, gender, and exposure to environmental tobacco smoke did not affect the concentration of ascorbate, urate, α-tocopherol, or protein carbonyls. However, in multiple linear regression analyses, the type of home heating (glass-fronted fires or oil-fired central heating) was found to influence ascorbate and urate concentrations in the BAL fluid (β-coefficient for ascorbate: 0.445, p = 0.031; for urate: 0.114, p = 0.001). There was no significant difference between the N and NA group in BAL fluid concentrations of ascorbate, urate, or protein carbonyls. The α-tocopherol concentration was significantly increased in the NA group (p = 0.037). Uric acid and α-tocopherol concentrations in BAL fluid and serum were not correlated. Intriguingly, serum and BAL ascorbate concentrations were significantly correlated (r = 0.297, p = 0.018, n = 63), which may offer an explanation for why supplementing the diet with vitamin C can improve asthma symptoms. Further studies will investigate the role of BAL antioxidant concentrations in children with inflammatory respiratory diseases.