IDENTICAL EXPRESSION OF ELAM-1, VCAM-1, AND ICAM-1 IN SARCOIDOSIS ANDUSUAL INTERSTITIAL PNEUMONITIS

Extravasation of leucocytes in tissues is mediated by leucocyte-endoth elial cell interactions in which adhesion molecules play an important role. Until now, two pathways have been unravelled, i.e., the LFA-1/IC AM-1 and the VLA-4/VCAM-1 pathways. ELAM-1 has been shown to be involv ed in granulocyte accumulation and recently also in lymphocyte migrati on. The role of HECA-452 is under investigation. In this study we have investigated the expression of the above-mentioned adhesion molecules in lung tissue of patients with pulmonary sarcoidosis and usual inter stitial pneumonitis (UIP), and in mediastinal lymph nodes of patients with sarcoidosis. ICAM-1 (CD54) was broadly distributed on the endothe lium of all the vessels found in sarcoidosis and UIP. VCAM-1 was prese nt on the endothelium of the venules, capillaries, and arterioles in b oth sarcoidosis and UIP. ELAM-1 reacted with endothelial cells lining venules and capillaries in chronic progressive sarcoidosis and in the active phase of UIP but not in the stationary phases of both diseases. HECA-452 activity could be detected only on high endothelial venules within sarcoid lymph nodes. In lung tissues, macrophages bearing the I CAM-1 antigen were present in sarcoid tissue but not in the interstiti um and alveolar space of UIP. LFA-1 (CD11a/CD18) and VLA-4 (CD49d/CD29 ) were present on all leucocytes found but seemed to be more highly ex pressed on lymphocytes in sarcoidosis. These findings suggest that the LFA-1/ICAM-1 and VLA-4/VCAM-1 pathways are involved in leucocyte migr ation in both types of lung disease, while in the active phases of sar coidosis and UIP, ELAM-1 is also involved.