BACKGROUND: The natural course of sarcoidosis is variable from spontaneous remission to significant morbidity or death. So the assessment of disease activity is important but no single parameter was generally accepted as a good marker. Recently several studies suggested that adhesion molecules, especially ICAM-1 can be a marker, but there are some controversies. And only few data are available about the relationship of ICAM-1 with clinical follow-up course. METHOD: We measured the expression of adhesion molecules on BAL cells by flow cytometry and the level of soluble ICAM-1 (sICAM-1) in serum and BALF at the time of diagnosis in 12 patients with active disease and 7 inactive sarcoidosis(5 male, 14 female, mean age : 39.4+/-10.7 years, mean follpw-up 20+/-15 months). Follow-up clinical course were compared with the changes in serum sICAMA-1 level and the adhesion molecule on BAL cells. RESULTS: In the patients with active disease, the ICAM-1 on AM(RMFI 3.68+/-1.71) and sICAM-1 level in serum(582+/-193 ng/ml) and BAL fluid(47.8+/-16.5 ng/ml) were all higher than those of 7 inactive disease(RMFI :1.89+/-0.75, p=0.0298, serum : 294+/-117 ng/ml, p=0.0049, BALF : 20.9+/-8.3ng/ml). In the active sarcoidosis, ICAM-1 on AM(RMFI:1.51+/-0.84) and serum sICAM-1 were decreased after the therapy(250+/-147 ng/ml) but no significant change was noted in inactive disease. Also we found the initial ICAM-1 on AM and serum sICAM-1 had a significant correlation with the degree of improvement in PFT after the therapy. During the follow-up, the disease relapsed in 4 patients after the discontinuation of steroid and the serum sICAM-1 level went-up again at the time of relapse. CONCLUSION: Our data suggest that the serum sICAM-1 level and the JCAM-1 expression on AM can be a good marker of disease activity and also a predictor of outcome in sarcoidosis.