Serum KL-6 in adult patients with polymyositis and dermatomyositis.

OBJECTIVE To determine the serum levels of KL-6, a mucin-like high-molecular-weight glycoprotein, in polymyositis/dermatomyositis (PM/DM) patients. METHODS Serum samples from 42 adult PM/DM patients and 38 healthy control subjects were examined using specific enzyme-linked immunosorbent assay (ELISA) systems. RESULTS The serum levels of KL-6 in the PM/DM patients were significantly higher than those of the healthy controls. The elevated serum KL-6 levels correlated with the presence of interstitial lung disease (ILD) and decreased percentage diffusing capacity of carbon monoxide (%DLco) in the PM/DM patients. The serum KL-6 levels inversely correlated with %DLco and percentage vital capacity. Additionally, the serum KL-6 levels were elevated in five of the seven DM patients with malignant neoplasia. CONCLUSIONS These results suggest that the serum KL-6 level might be a useful serum marker for ILD and internal malignancy in PM/DM.