Elevated serum soluble CD44 level in sarcoidosis

Sarcoidosis is a chronic multi-organ granulomatous disease of unknown etiol ogy. Several studies have suggested an involvement of immunologic backgroun d in sarcoidosis. The lymphocyte surface marker CD44 is a multifunctional m olecule which mediates the adhesion of lymphocytes to the extracellular mat rix. Recently, we developed a system to quantitate soluble CD44 (sCD44) whi ch we employed to determine serum and bronchoalveolar lavage fluid (BALF) l evels of sCD44 to obtain further insights into immunologic aspects of sarco idosis. Serum sCD44 levels were measured in 13 consecutive patients with sa rcoidosis and 56 normal healthy controls using enzyme-linked immunoabsorben t assay. BALF sCD44 levels were also measured in 11 patients with sarcoidos is 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 1 8.1+/-8.4 ng/ml), but no statistically significant difference was recognize d. We also found that there was a positive correlation between the serum sC D44 and angiotensin converting enzyme (r=0.78). Our data indicate that sCD4 4 may be related to immunologic background and may be a useful new marker o f sarcoidosis.