Possible role of L-selectin in T lymphocyte alveolitis in patients with active pulmonary sarcoidosis

A number of adhesion molecules participate in the recruitment of inflammato ry cells to the site of inflammation, and selectins together with their lig ands are important in the early transient adhesion phase. In this study, we evaluated the role of L-selectin in T lymphocyte alveolitis in patients wi th active pulmonary sarcoidosis. We measured serum and bronchoalveolar lava ge fluid (BALF) concentrations of soluble (s)L-selectin using an ELISA. Ser um and BALF concentrations of sL-selectin were significantly elevated in pa tients with sarcoidosis compared with control healthy subjects and idiopath ic pulmonary fibrosis (IPF) patients (P < 0.05 and P < 0.01, respectively). The lymphocyte surface marker was also examined in peripheral blood and BA LF by flow cytometric analysis. The percentage of CD3(+)CD62L(+) cells (L-s electin-bearing T lymphocytes) was significantly lower in peripheral blood of sarcoidosis than in that of healthy subjects (P < 0.01). In contrast, th e percentage of CD3(+)CD62L(-) cells (L-selectin-negative T lymphocytes) in BALF of patients with sarcoidosis was significantly higher than in healthy subjects (P < 0.05) and IPF patients (P < 0.01). Furthermore, there was a significant correlation between serum concentrations of sL-selectin and the number of L-selectin-negative T lymphocytes in BALF (r = 0.535, P < 0.01). Our results suggest that L-selectin may be involved in T lymphocyte alveol itis in patients with active pulmonary sarcoidosis.