SYNOPSIS
Chemokines regulate the homeostatic trafficking of lymphocytes and lymphocyte influx into sites of injury and inflammation. Chemokines can induce rapid changes in integrin-dependent adhesion. Although activation of phosphatidy-linositol 3-kinase (PI 3-K) is critical to integrin activation induced by Ig superfamily members such as CD2, CD3 and CD28, the role of PI 3-K in chemokine-induced integrin activation is unclear. We examined the role of PI 3-K in several functional responses induced by ligation of the CXCR4 chemokine receptor expressed on Jurkat T cells with the CXC chemokine stromal cell-derived factor-1 a (CXCL12). Enhanced Jurkat cell adhesion induced by CXCL12 was inhibited by pertussis toxin and by the PI 3-K inhibitors, wortmannin and LY294002. CXCL12 also in-duced F-actin polymerization on Jurkat cells that was only partially inhibited by PI 3-K inhibitors. In contrast, CXCL12 -mediated phosphorylation of the PI 3-K-dependent enzyme AKT was markedly prolonged, with AKT activation being detectable as late as 60 min.

Key words: Integrin, CXC chemokine, Adheion