Mycobacterium-induced transmesothelial migration of monocytes into pleuralspace: Role of intercellular adhesion molecule-1 in tuberculous pleurisy

The pleural mesothelium is a dynamic cellular membrane with multiple key fu nctions, it plays a pivotal role in pleural inflammation through its releas e of several cytokines and the expression of cell-surface molecules. The ex pression of intercellular adhesion molecule (ICAM)-1 in the pleural mesothe lium of patients with active pleural tuberculosis and the role of ICAM-1 in monocyte transmigration across pleural mesothelium during tuberculous infl ammation was investigated. Results indicate pleural mesothelial cells (PMCs ) express ICAM-1 in tuberculous pleuritis. When PMCs were stimulated with b acille Calmette-Guerin (BCG) in vitro, they expressed ICAM-1 in a time-depe ndent manner. Monocyte transmigration was higher across PMC monolayers that had been stimulated with BCG. Blocking ICAM-1 on BCG-activated PMC monolay ers inhibited monocyte transmigration against chemotactic gradient generate d by macrophage inflammatory protein 1-alpha or monocyte chemotactic protei n-1. These results indicate that ICAM-1 expression in PMCs facilitates mono cyte transmigration during tuberculous pleural inflammation.