To examine the effects of corticosteroid treatment on lavage type 3 procollagen peptide levels, 14 treated patients and eight untreated patients were relavaged. A decrease in median type 3 procollagen peptide levels was observed following treatment (before treatment median, 1.39 and range, 0 to 20.2; after treatment median, 0.54 and range, 0 to 34.1). However, this decrease did not reach the level of significance as assessed by paired statistical tests and a similar nonsignificant decrease in procollagen peptide levels was also observed in untreated patients (first lavage median, 1.84 and range, 0.3 to 10.8; second lavage median, 1.0 and range, 0 to 18.5). Pulmonary function tests indicated a positive response to corticosteroid therapy in the treated patients.
Elevated type 3 procollagen peptide levels, similar to those observed in this study, have been noted in the bronchoalveolar lavage fluids of sarcoid patients by previous investigators and have been shown to reflect local metabolism of collagen in the lung.- In a more recent study, Cantin et al failed to observe a significant increase in lavage type 3 procollagen peptide levels in a group of 59 patients with sarcoidosis, although some patients did display elevated levels. Considerable variation in lavage type 3 procollagen peptide levels were observed within the sarcoid group in the present study, indicating that, in any examination of lavage type 3 procollagen peptide in sarcoidosis, the observed levels will rely heavily on the patient group chosen for study. This may explain the discrepancy between the results of Cantin et al and those of other investigators.
In sarcoidosis patients, we noted a positive correlation between lavage levels of type 3 procollagen peptide, fibronectin and ACE, and to a lesser extent, between lavage type 3 procollagen peptide and serum ACE. The association between elevated ACE levels and sarcoidosis is well documented. The ACE is produced by the epithelioid and giant cells of the sarcoid granuloma and is thought to reflect the tissue granuloma burden. An increase in type 3 relative to type 1 collagen has been observed in early granulation tissue; thus, the observed association between lavage type 3 procollagen peptide and ACE may reflect altered production of type 3 collagen in the lung granuloma.