The development of bleomycin-induced lung injury, which is a model of pulmonary fibrosis, results from inflammatory cell infiltration, a process highly regulated by the expression of multiple adhesion molecules. Therefore, bleomycin-induced lung fibrosis was examined in E-selectin ؊/؊ mice, P-selectin ؊/؊ mice, and E-selectin ؊/؊ mice treated with anti-P-selectin monoclonal antibody (mAb) in comparison of wild-type mice. E-selectin ؊/؊ mice treated with anti-P-selectin mAb exhibited augmented lung fibrosis histologically, increased lung collagen deposition, and increased mortality compared to wild-type mice. Furthermore, lung interferon-␥ mRNA expression decreased in E-selectin ؊/؊ mice treated with anti-P-selectin mAb relative to wild-type mice, while tumor necrosis factor-␣ and interleukin-6 mRNA expression increased in these mice. Similar changes were observed in E-selectin ؊/؊ mice, albeit to a lesser extent than those treated with anti-P-selectin mAb. Remarkably, flow cytometric analysis revealed that the frequency of interferon-␥-producing natural killer T (NKT) cells in the bronchoalveolar lavage was decreased in E-selectin ؊/؊ mice and E-selectin ؊/؊ mice treated with anti-P-selectin mAb compared with wildtype mice. Moreover, the majority of NKT cells expressed high levels of CXCR3, suggesting that NKT cell infiltration is also dependent on CXCR3 expression. These results suggest that E-and P-selectins synergistically inhibit lung fibrosis by promoting the recruitment of NKT cells.