We wanted to determine whether cell populations and soluble components in bronchoalveolar lavage (BAL) could be useful in predicting the outcome of lung function and chest radiography in patients with untreated pulmonary sarcoidosis. Analysis of soluble proteins in BAL fluid, included the levels of immunoglobulins and the two major antiproteases, alpha 2-macroglobulin (alpha 2-M) and alpha 1-protease inhibitor (alpha 1-PI), expressed as a relative coefficient of excretion (RCE). Thirty one nonsmoking patients with biopsy proven sarcoidosis, who remained untreated, had reassessment of lung function tests after 6-54 months (median 21 months). No correlation was observed between initial BAL data and changes in lung volumes and radiographic opacities. By contrast, the initial BAL immunoglobulin A and G (IgA and IgG) RCE correlated inversely with the change in transfer factor for carbon monoxide (TLCO) in the whole group and in patients with sarcoidosis of recent origin (estimated disease duration < 6 months). In the whole group and in patients with longstanding disease (estimated disease duration > 24 months, or radiographic Stage 4), the change in carbon monoxide transfer coefficient (KCO) correlated negatively with the initial alpha 1-PI RCE and positively with the initial helper to suppressor T-cell (T4/T8) ratio. By contrast, no significant difference in BAL cellular and protein data was found between patients with recent and longstanding sarcoidosis.(ABSTRACT TRUNCATED AT 250 WORDS)