Interferon‐γ stimulates the expression of galectin‐9 in cultured human endothelial cells

Galectin‐9 is a member of the galectin family and has been identified as an eosinophil chemoattractant produced by activated T lymphocytes. Vascular endothelial cells play an important role in the initial step of eosinophil recruitment and activation in immune and inflammatory responses. We have addressed the stimulation of galectin‐9 expression in endothelial cells. Galectin‐9 was detected in membrane and cytosolic fractions of human umbilical vein endothelial cells stimulated with interferon‐γ (IFN‐γ). IFN‐γ also enhanced the adhesion of human eosinophilic leukemia‐1 cells to endothelial monolayers, and it was inhibited by the presence of lactose. Interleukin‐4, which induces eotaxin expression, did not affect the expression of galectin‐9. The in situ endothelium from patients with inflammatory diseases was found to express galectin‐9. IFN‐γ‐induced production of galectin‐9 by endothelial cells may play an important role in immune responses by regulating interactions between the vascular wall and eosinophils.