CXCL9 and 11 in patients with pulmonary sarcoidosis: a role of alveolar macrophages

Summary Interferon‐inducible protein‐10 (IP‐10)/CXCL10, which is a ligand for CXC chemokine receptor 3 (CXCR3), is known to be involved in the pathogenesis of pulmonary sarcoidosis. However, the roles of monokine induced by interferon γ (Mig)/CXCL9 and interferon‐inducible T cell α chemoattractant (I‐TAC)/CXCL11, which are also CXCR3 ligands, remain unclear. Mig/CXCL9, IP‐10/CXCL10 and I‐TAC/CXCL11 in both bronchoalveolar lavage fluid (BALF) and serum in patients with pulmonary sarcoidosis were measured by enzyme‐linked immunosorbent assay (ELISA). The expression of these chemokines in alveolar macrophages was examined using ELISA, quantitative real‐time polymerase chain reaction and immunostaining. In BALF, Mig/CXCL9 and IP‐10/CXCL10 were significantly elevated in stage II sarcoidosis as compared with the levels in healthy volunteers. In serum, Mig/CXCL9 and I‐TAC/CXCL11 were increased in stage II of the disease. The levels of all CXCR3 ligands in BALF were correlated with the numbers of both total and CD4 + lymphocytes. Alveolar macrophages were stained positive for all CXCR3 ligands and produced increased amounts of these chemokines. Positive staining of the three chemokines was also observed in the epithelioid and giant cells in the sarcoid lungs. These findings suggest that Mig/CXCL9 and I‐TAC/CXCL11 as well as IP‐10/CXCL10 play important roles in the accumulation of Th1 lymphocytes in sarcoid lungs.