Interferon-gamma 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-gamma (IFN-gamma). IFN-gamma 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-gamma-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.