CD43 collaborates with P-selectin glycoprotein ligand-1 to mediate E-selectin-dependent T cell migration into inflamed skin.

Activated T cell migration into nonlymphoid tissues is initiated by the interactions of P- and E-selectin expressed on endothelial cells and their ligands on T cells. P-selectin glycoprotein ligand-1 (PSGL-1) has been the only E-selectin ligand demonstrated to function during the in vivo migration of activated T cells. We show in this study that CD43-deficient Th1 cells, like PSGL-1-deficient cells, exhibited reduced E-selectin-binding activity compared with wild-type cells. Th1 cells with a PSGL-1 and CD43 double deficiency showed even less E-selectin-binding activity. In migration assays in which adoptively transferred cells migrate to inflamed skin P- and E-selectin dependently, CD43 contributed significantly to PSGL-1-independent Th1 cell migration. In addition, in vivo activated T cells from the draining lymph nodes of sensitized mice deficient in PSGL-1 and/or CD43 showed significantly decreased E-selectin-binding activity and migration efficiency, with T cells from double-deficient mice showing the most profound decrease. Collectively, these results demonstrate that the CD43 expressed on activated T cells functions as an E-selectin ligand and thereby mediates T cell migration to inflamed sites, in collaboration with PSGL-1.