CUTTING EDGE - SELECTIVE UP-REGULATION OF CHEMOKINE RECEPTORS CCR4 AND CCR8 UPON ACTIVATION OF POLARIZED HUMAN TYPE-2 TH CELLS

Polarized Th1 and Th2 cells differentially express adhesion molecules and chemokine receptors, endowing these cells with distinct tissue hom ing capabilities. Here we report that, in contrast to other chemokine receptors, the expression of CCR4 and CCR8 on Th2 cells is transiently increased following TCR and CD28 engagement. IL-4 is not required for this activation-induced upregulation of CCR4 and CCR8, In accordance with receptor expression, the response of Th2 cells to I-309 (CCR8 lig and) and thymus- and activation-regulated chemokine (CCR4 and CCR8 lig and) is enhanced upon activation, Moreover, activated Th1 cells up-reg ulate CCR4 expression and functional responsiveness to thymus- and act ivation-regulated chemokine, Analysis of polarized subsets of CD8(+) T cells reveals a similar pattern of chemokine receptor expression and modulation of responsiveness. Taken together, these findings suggest t hat an up-regulation of CCR4 and CCR8 following Ag encounter may contr ibute to the proper positioning of activated T cells within sites of a ntigenic challenge and/or specialized areas of lymphoid tissues.