Pro-oxidant iron in exhaled breath condensate: a potential excretory mechanism

Aims: Pro-oxidant iron provides a potential measure of iron-catalysed oxidative stress in biological fluids. This study aimed, to investigate if the Bleomycin technique for measurement of pro-oxidant iron in biological fluids could be utilised for determinations in exhaled breath condensate (EBC). Secondly, to measure levels of pro-oxidant iron in EBC from asthmatics after exposure to polluting city environments.

Methods: Retrospective analysis of samples of EBC and bronchoalveolar lavage fluid (BALF). Pro-oxidant iron levels were determined by the Bleomycin method. Transferrin levels were determined by radial diffusion immunoassay and lactoferrin by ELISA.

Subjects: Patients undergoing surgery necessitating cardiopulmonary bypass, normal healthy controls, "healthy" smokers, and asthmatics (mild and moderate).

Results: Pro-oxidant iron was significantly decreased (p<0.05) post cardiac surgery in both EBC and BALF. In smokers levels of pro-oxidant iron in EBC were significantly (p<0.05) increased verses healthy controls. In asthmatics with more severe disease, there were significant increases in EBC pro-oxidant iron content post exposure to city environments (p<0.001), with levels most elevated after exposure to the most polluted setting.

Conclusion: Similar patterns in the levels of pro-oxidant iron detectable in EBC and paired BALF from patients undergoing cardiopulmonary bypass (pre and post surgery) suggest a potential for EBC determinations. Significantly elevated levels in EBC from smokers relative to control subjects provide further support for this technique. In asthma disease severity and environmental exposure influenced levels of pro-oxidant iron measured in EBC indicating a potential for enhanced iron-catalysed oxidative stress.