CTACK, a skin-associated chemokine that preferentially attracts skin-homing memory T cells

In contrast to naive lymphocytes, memory/effector lymphocytes can access no nlymphoid effector sires and display restricted, often tissue-selective, mi gration behavior. The cutaneous lymphocyte-associated antigen (CLA) defines a subset of circulating memory T cells that selectively localize in cutane ous sites mediated in part: by the interaction of CLA with its vascular lig and E-selectin. Here, we report the identification and characterization of a CC chemokine, cutaneous T cell-attracting chemokine (CTACK), Both human a nd mouse CTACK are detected only in skin by Southern and Northern blot anal yses. Specifically, CTACK message is found in the mouse epidermis and in hu man keratinocytes, and anti-CTACK mAbs predominantly stain the epithelium. Finally, CTACK selectively attracts CLA(+) memory T cells. Taken together, these results suggest an important role for CTACK in recruitment of CLA(+) T cells to cutaneous sites. CTACK is predominantly expressed in the skin an d selectively attracts a tissue-specific subpopulation of memory lymphocyte s.