PROTEIN PROFILE IN BRONCHOALVEOLAR LAVAGE FLUID FROM PATIENTS WITH SARCOIDOSIS AND IDIOPATHIC PULMONARY FIBROSIS AS REVEALED BY SDS-PAGE ELECTROPHORESIS AND WESTERN-BLOT-ANALYSIS

So far bronchoalveolar lavage (BAL)-protein in interstitial lung disea se (ILD) is evaluated by measuring concentrations of single proteins. Due to the high dilution of most proteins in BAL, analysis of protein profile has been disappointing. This study describes a new method to o vercome this problem and to reveal a highly differentiated picture of BAL proteins. Eighteen patients with pulmonary sarcoidosis, 18 patient s with idiopathic pulmonary fibrosis (IPF) and 22 patients with no cli nical, roentgenologic or functional evidence of ILD underwent BAL. Tot al and differential cell count was performed. Normal values for the co ntrol group, a lymphocytic alveolitis in sarcoidosis and a granulocyti c alveolitis in IPF-patients were found. Median total protein concentr ation in sarcoidosis showed an increase five times higher than that of the controls (150 mg l-1 and 27 mg l-1, respectively) with p < 0.001, IPF protein concentration (58 mg l-1) exceeded twice the control valu es (0.01 > p > 0.001). Analysis of electrophoretic protein profile in controls with Western blot analysis and the biotin/streptavidin staini ng system revealed a highly differentiated range of bands. Staining wi th immunoglobulin antibody identified six bands. Four proteins with mo lecular weight < 21.000 dalton were present only in sarcoidosis patien ts. These proteins may be identical with fragmented serum proteins or different cell mediators detected in alveolar cell supernatants. Furth ermore, in sarcoidosis the intensity and number of bands with molecula r weight more than 67.000 dalton was increased. This gives strong evid ence for an injury of the alveolar membrane integrity in the alveoliti s during the course of sarcoidosis. The uniform protein profile in IPF compared to the highly variable profile and increased band intensity in sarcoidosis stresses the different pathogenesis of these ILDs. West ern blot analysis of BAL-protein profile is a highly promising method to assess pathogenetic changes, alveolar membrane integrity, and leaka ge in interstitial lung disease.