Chest, Vol 98, 1414-1420, Copyright © 1990 by American College of Chest Physicians

ARTICLES

Elevated serum procollagen III aminopeptide levels in sarcoidosis

M Luisetti, A Bulgheroni, L Bacchella, L Pasturenzi and C Aprile
Istituto di Tisiologia e Malattie Respiratorie, IRCCS Policlinico San Matteo, Universita di Pavia, Italy.

Procollagen III aminopeptide (P-III-P), a peptide released during the conversion of type III procollagen to type III collagen, is considered a potential marker of fibroblast activity in a variety of pulmonary and extrapulmonary diseases. The aim of the present article was to investigate the levels of P-III-P in serum samples (sP-III-P) from a large number of sarcoid patients, in particular looking at its relationship with other markers of disease activity and its presumed role as a marker of pulmonary fibrosis. sP-III-P has been radioimmunoassayed in an overall series of 57 patients and the levels were higher (19.18 +/- 9.17 ng/ml) than in 25 age- and sex-matched controls (11.32 +/- 2.15 ng/ml; p less than 0.001). The elevation was neither sex-related nor related to obvious liver sarcoid localization. Although sP-III-P levels were slightly higher in patients with stage II, there was no significant difference in patients with stage I or III. We found a positive relationship with serum angiotensin-converting enzyme (S-ACE) levels (p less than 0.04), but not with other markers of disease activity (67Ga uptake, bronchoalveolar lavage [BAL] lymphocyte percent, vital capacity, and lung diffusing capacity). The relationship with S-ACE was confirmed in a longitudinal follow-up study, where sP- III-P strictly paralleled the S-ACE behavior. Finally, the initial sP- III-P levels did not predict cases either with disease relapse or resistance to corticosteroid treatment. We conclude that, in our study, sP-III-P levels failed to characterize sarcoid patients with radiologic fibrotic pattern (stage III), and, in addition, were unable to predict which patients would have a poor prognosis. Rather, they reflect a metabolic activity of sarcoid granuloma cells. Thus, the usefulness of sP-III-P in the treatment of patients with sarcoid may be considered similar to that of S-ACE.

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