Bovine γδ T Cell Subsets Express Distinct Patterns of Chemokine Responsiveness and Adhesion Molecules: A Mechanism for Tissue-Specific γδ T Cell Subset Accumulation

Abstract

Subsets of γδ T cells localize to distinct tissue sites in the absence of exogenous Ag stimulation or development of effector/memory cells. Selective lymphocyte homing from the blood into tissues is controlled by a multistep process involving vascular and lymphocyte adhesion molecules, and G protein-linked chemokine receptors. The role of these mechanisms in the tissue tropism of γδ T cells is still poorly understood. In this study, we demonstrate that a subset of γδ T cells, most of which express an antigenically distinct TCR and are characterized by coexpression of CD8, selectively accumulated in tissues that expressed high levels of the mucosal vascular addressin, mucosal addressin cell adhesion molecule 1. These cells expressed higher levels of α4β7 integrins than other γδ T cell subsets and selectively migrated to the CCR7 ligand secondary lymphoid-tissue chemokine (CCL21). Integrin activation by CCL21 selectively increased CD8+γδ T cell binding to recombinant mucosal addressin cell adhesion molecule 1. These results suggest that the tropism of circulating CD8+γδ T cells for mucosal tissues is due, at least in part, to selective developmental expression of adhesion molecules and chemokine receptors.