Expression of IFN-Inducible T Cell α Chemoattractant by Human Endothelial Cells Is Cyclosporin A-Resistant and Promotes T Cell Adhesion: Implications for Cyclosporin A-Resistant Immune Inflammation

IFN-inducible T cell alpha chemoattractant (I-TAC) is a recently discovered member of the CXC chemokine family. It is a potent T cell chemoattractant expressed by IFN-gamma-treated astrocytes, monocytes, keratinocytes, bronchial epithelial cells, and neutrophils. In this study, we show that I-TAC is also expressed by IFN-gamma-treated endothelial cells (EC), both at the mRNA and protein levels. Induction of the I-TAC message is rapid and sustained over 24 h. TNF-alpha does not induce I-TAC mRNA alone, but does act synergistically with IFN-gamma. Blocking Abs to I-TAC, or to its receptor, CXCR3, reduce T cell adhesion to EC monolayers demonstrating that the expressed protein is functional. Finally, the expression of I-TAC by EC is resistant to the immunosuppressive drug cyclosporin A, suggesting that I-TAC may contribute to the chronic immune inflammation characteristic of graft arteriosclerosis.