The chemokine interferon (IFN)-gamma-inducible protein of 10 kDa (IP-10; CXCL10) has been implicated in recruitment of T cells into rejecting allografts yet appears ineffective at stimulating human peripheral blood CD4 T cells to transmigrate across tumor necrosis factor (TNF)-treated human endothelial cell (EC) monolayers in vitro. The same cells rapidly (within 15 min) transmigrate across TNF-treated EC monolayers overlaid with stromal cell-derived factor-1 alpha (SDF-1 alpha) and subjected to shear stress. The effector memory subset within the CD4 T cell population, defined as CD45RO, CD62L and CCR7, which constitutes less than 10% of total CD4 T cells, does respond to IP-10 but requires enrichment to be observed in this model. Central memory T cells do not respond to IP-10. Transendothelial migration of effector memory CD4 T cells requires TNF-pretreatment of the EC monolayer and application of venular shear force during the assay. TNF treatment of ECs may be effectively replaced by transduction of vascular cell adhesion molecule-1 or intercellular adhesion molecule-1 but not E-selectin.