[Serum CA 19-9 levels in rheumatic diseases with interstitial pneumonia]

Serum CA 19-9 (2-3 sialyl Le(a)) is a marker of malignant disorder such as pancreas or gall bladder cancers. It has been reported that sera from patients with interstitial pneumonia show elevated level of CA 19-9. To investigate the relationship between the elevation of serum CA 19-9 (sCA 19-9) and the presence of pulmonary fibrosis, we examined the level of sCA 19-9 in sera from patients with rheumatic diseases with or without interstitial pneumonia (IP). The sCA 19-9 level was determined by enzyme-linked immunosorbent assay (ELISA). Fourteen sera of 129 (10.9%) patients with rheumatic diseases without malignant disorders were positive for sCA 19-9 when normal range was determined as less than 100 U/ml (mean +/- 5 SD), and 26.7% of sera from poly/dermatomyositis (PM/DM) and 11.8% of systemic sclerosis (PSS) were positive for CA 19-9. Whereas only 8.0% of rheumatoid arthritis (RA) was positive. Twelve (28.6%) of 42 rheumatic patients with IP showed positive levels for sCA 19-9 (mean 142.5 +/- 363.0 U/ml), whereas only two (2.3%) of 87 without IP were positive (mean 33.9 +/- 65.8 U/ml; p < 0.05). The correlation between the level of sCA 19-9 and pulmonary diffusing capacity (%DLCO) revealed an inverse correlation in 32 rheumatic patients with IP (r = -0.43, p < 0.05). Furthermore, the elevated sCA 19-9 levels decreased after treatment with corticosteroid and/or cyclophosphamide or cyclosporin A. Therefore, elevation of the level of sCA 19-9 seems to be involved in the pathogenesis of IP and sCA 19-9 will be a useful parameter for IP. It has been reported that the CA 19-9 is produced from the bronchial glands and suggested that during chronic fibrotic process of the lung, the metaplastic change of the bronchial glandular cells occur and the cells produce CA 19-9.