Elevated levels of soluble ICAM-1 in serum and BAL fluid in patients with active sarcoidosis.

Intercellular adhesion molecule-1 (ICAM-1), a member of the immunoglobulin superfamily of adhesion molecules, plays an important role in inflammatory and immune diseases. The soluble form of ICAM-1 (sICAM-1) shed from the cell surface may be a marker of inflammatory response and may reflect the disease activity. We measured the levels of sICAM-1 in serum and bronchoalveolar lavage fluid (BALF) in patients with sarcoidosis. Healthy volunteers were examined as controls. sICAM-1 concentrations were measured using an enzyme-linked immunosorbent assay kit with two different monoclonal antibodies. Serum and BALF sICAM-1 levels in sarcoidosis were significantly higher than those in control. Serum sICAM-1 levels correlated with serum soluble interleukin-2 receptor levels (a marker of T-lymphocyte activation) but not with serum angiotensin-converting enzyme levels. sICAM-1 levels in BALF correlated significantly with the percentage of lymphocytes in BALF. Some patients were examined twice during follow-up periods. In patients in whom the chest radiograph improved, serum and BALF sICAM-1 levels decreased. However, in patients in whom the radiograph worsened, sICAM-1 levels increased. These results suggest that measurement of sICAM-1 may be useful to investigate not only the pathogenic mechanisms, but also the clinical status and disease activity in patients with sarcoidosis.