Activation of phosphoinositide 3-kinases by the CCR4 ligand macrophage-derived chemokine is a dispensable signal for T lymphocyte chemotaxis.

Macrophage-derived chemokine (MDC/CC chemokine ligand 22 (CCL22)) mediates its cellular effects principally by binding to its receptor CCR4, and together they constitute a multifunctional chemokine/receptor system with homeostatic and inflammatory roles in the body. We report the CCL22-induced accumulation of phosphatidylinositol-(3,4,5)-trisphosphate (PI(3,4,5)P(3)) in the leukemic T cell line CEM. CCL22 also had the ability to chemoattract human Th2 cells and CEM cells in a pertussis toxin-sensitive manner. Although the PI(3,4,5)P(3) accumulation along with the pertussis toxin-susceptible phosphorylation of protein kinase B were sensitive to the two phosphoinositide 3-kinase inhibitors, LY294002 and wortmannin, cell migration was unaffected. However, cell migration was abrogated with the Rho-dependent kinase inhibitor, Y-27632. These data demonstrate that although there is PI(3,4,5)P(3) accumulation downstream of CCR4, phosphoinositide 3-kinase activity is a dispensable signal for CCR4-stimulated chemotaxis of Th2 cells and the CEM T cell line.