Fibrosing alveolitis (FA) is a common and often fatal complication of systemic sclerosis (SSC). The purpose of this study was to characterize the fibrotic process within the lungs using bronchoalveolar lavage fluid (BALF). We investigated 25 healthy controls (CON) and 85 SSC patients. In 61 patients (72%) lung function tests, clinical, and radiological findings indicated manifest FA, whereas 24 patients (28%) where free of significant lung disease. Of the latter, 12 had pathologic BAL differential cell counts (= subclinical alveolitis; SUB), 12 had normal BAL cytology (NOR). BAL samples were analysed for chemoattractant activity (CAA) for fibroblasts using Boyden chambers. Procollagen-III-Peptide (P-III-P) and Laminin fragment P1 (Lam-P1) were measured radioimmunologically. CAA (expressed as % of the effect of conditioned medium) was increased in FA and SUB (CON: 17.3 +/- 3.2; FA: 40.8 +/- 5.8, p < 0.01 vs. CON; SUB: 58.6 +/- 11.8, p < 0.01 vs. CON; NOR: 23.7 +/- 6.3; n.s.). Lam-P1 [U/ml ELF] was also elevated in FA and SUB patients (CON: 0.90 +/- 0.17; FA: 2.07 +/- 0.48, p < 0.05 vs. CON; SUB: 2.61 +/- 1.14, p < 0.05 vs. CON; NOR: 1.05 +/- 0.35, n.s. vs. CON). P-III-P [U/ml ELF] was elevated in FA patients (CON: 8.3 +/- 1.1; FA: 26.9 +/- 5.5, p < 0.001 vs. CON) but not in SUB or NOR (SUB: 10.2 +/- 0.7, NOR: 7.9 +/- 2.9; n.s.). There was no significant relationship between P-III-P and LAM-P1 values in ELF and serum, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)