Sarcoidosis is a chronic multi-organ granulomatous disease of unknown etiology. Several studies have suggested an involvement of immunologic background in sarcoidosis. The lymphocyte surface marker CD44 is a multifunctional molecule which mediates the adhesion of lymphocytes to the extracellular matrix. Recently, we developed a system to quantitate soluble CD44 (sCD44) which we employed to determine serum and bronchoalveolar lavage fluid (BALF) levels of sCD44 to obtain further insights into immunologic aspects of sarcoidosis. Serum sCD44 levels were measured in 13 consecutive patients with sarcoidosis and 56 normal healthy controls using enzyme-linked immunoabsorbent assay. BALF sCD44 levels were also measured in 11 patients with sarcoidosis and 10 normal healthy controls. In patients with sarcoidosis, the serum sCD44 level was significantly higher than that of normal controls (348.5+/-164.2 ng/ml vs 145.4+/-22.9 ng/ml; p<0.001). Also BALF sCD44 levels tended to be higher in sarcoidosis than in normal controls (23.7+/-13.4 ng/ml vs 18.1+/-8.4 ng/ml), but no statistically significant difference was recognized. We also found that there was a positive correlation between the serum sCD44 and angiotensin converting enzyme (r=0.78). Our data indicate that sCD44 may be related to immunologic background and may be a useful new marker of sarcoidosis.

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