Ly6C supports preferential homing of central memory CD8⁺ T cells into lymph nodes

AbstractLy6C is a murine cell‐surface antigen expressed by plasma cells, subsets of myeloid cells and many T cells, including memory T cells. We previously documented that Ly6C crosslinking induces LFA‐1 clustering on naïve CD8+ T cells. Here, we show that in vitro and in vivo differentiation of naïve CD8+ T cells into central (Tcm) but not effector (Tem) memory T cells enhances Ly6C expression, and its crosslinking induces strong LFA‐1 clustering on Tcm. Blocking Ly6C function inhibits in vivo Tcm homing to LNs as efficiently as blocking L‐selectin but it does not potentiate the inhibition provided by blocking either L‐selectin or LFA‐1 function. Thus, Ly6C, L‐selectin and LFA‐1 all appear to be part of a common homing pathway. In vitro, Ly6C crosslinking enhances Tcm adherence to ICAM‐1 in the presence of CCL21. In summary, Tcm homing involves Ly6C, in addition to L‐selectin and LFA‐1, and appears to potentiate firm adhesion of Tcm to ICAM‐1 in synergy with a chemokine. We propose that Ly6C augments Tcm compartmentalization into LNs during their homing.