OXIDIZED BAL FLUID PROTEINS IN PATIENTS WITH INTERSTITIAL LUNG-DISEASES

Oxygen-derived free radicals, released by phagocytic cells, have been postulated to contribute to lung tissue damage. We therefore investiga ted oxidative damage to proteins from bronchoalveolar lavage fluid (BA LF) as an indicator of oxidative stress and to assess antioxidant defe nces in the lungs. We examined BAL fluids from patients with interstit ial lung diseases, such as idiopathic pulmonary fibrosis (IPF, nonsmok ers (NS) and smokers (S)), sarcoidosis (SARC, nonsmokers), and asbesto sis (ASB, ex-smokers (EXS)). The oxidation of BALF proteins is accompa nied by the introduction of carbonyl groups into their amino acid side -chains and can be quantitated by labelling these groups with tritiate d borohydride. The total lung content of oxidized proteins recovered b y bronchoalveolar lavage (BAL) was 0.3+/-0.07 nmol carbonyl . mL BALF (mean+/-SEM) in the NS control group (n=9) and tended to be increased, in the asymptomatic S group (m=8; 0.59+/-0.14 nmol . mL(-1)). This pa rameter was significantly elevated both in IPF-NS (n=14; 0.84+/-0.2 nm ol carbonyl . mL(-1) BALF) and SARC-NS (n=15; 0.73+/-0.16 nmol . mL(-1 )) as compared with NS control. On the contrary, in smoking patients w ith IPF (n=6; 0.41+/-0.1 nmol carbonyl . mL(-1) BALF) and also in ASB- EXS (n=6; 0.73+/-0.16 nmol . mL(-1)) it was not different from NS cont rols. The total amount of oxidized proteins correlated positively with the absolute number of eosinophils (EOS) in IPF-NS, IPF-S and SARC an d also with absolute polymorphonuclear neutrophil (PMN) numbers in IPF -NS and IPF-S. In conclusion, oxidative damage of BALF proteins occurr ed in nonsmoking patients with IPF and SARC. The amount of oxidized br onchoalveolar lavage fluid protein may provide a quantitative assessme nt of oxygen burden, a balance between oxidant stress and antioxidant defences.