Glutathione depletion in epithelial lining fluid of lung allograft patients

The lower respiratory tract is protected against reactive oxygen species (ROS) by a complex antioxidant system. In the epithelial lining fluid (ELF), glutathione (L-alpha-glutamyl-L-cysteinylglycine, GSH) is essential for adequate protection of pneumocytes from potential toxicity mediated by extracellular hydrogen peroxide (H2O2). We assessed the concentration of total GSH in bronchoalveolar lavage fluid (BALF) in lung allograft patients in the absence and presence of acute rejection. Bronchoalveolar lavage (BAL) and biopsies were performed concurrently on 36 occasions in 17 patients who had undergone lung transplantation. BALF samples were divided into two groups on the basis of presence or absence of acute lung rejection on transbronchial biopsy. Seven BALF samples were obtained from control subjects for comparison. The BALF data demonstrated significantly lymphocyte recruitment and evidence of lung injury during acute rejection episodes. Transplant allografts without rejection showed significant depletion of total GSH in the ELF as compared with that of normal volunteers (94.0 +/- 9.7 microM versus 302.6 +/- 40.8 microM, p < 0.01). Transplant allografts with acute rejection had a slightly higher GSH concentration in their ELF (179.8 +/- 34.7), but this was still lower than control values. The deficiency of total GSH in the alveolar fluid may predispose lung allografts to extracellular H2O2-mediated toxicity.