CD46-induced immunomodulatory CD4+ T cells express the adhesion molecule and chemokine receptor pattern of intestinal T cells.

Tissue homing of activated T cells is typically mediated through their specific integrin and chemokine receptor repertoire. Activation of human primary CD4(+) T cells in the presence of CD46 cross-linking induces the development of a distinct immunomodulatory T cell population characterized by high IL-10/granzyme B production. How these regulatory T cells (Tregs) migrate/home to specific tissue sites is not understood. In this study, we determined the adhesion protein and chemokine receptor expression pattern on human CD3/CD46-activated peripheral blood CD4(+) T cells. CD3/CD46-activated, but not CD3/CD28-activated, T cells up-regulate the integrin alpha(4)beta(7). The interaction of alpha(4)beta(7) with its ligand mucosal addressin cell adhesion molecule 1 (MAdCAM-1) mediates homing or retention of T cells to the intestine. CD3/CD46-activated Tregs adhere to/roll on MAdCAM-1-expressing HeLa cells, similar to T cells isolated from the human lamina propria (LP). This interaction is inhibited by silencing MAdCAM-1 expression in HeLa cells or by the addition of blocking Abs to beta(7). CD46 activation of T cells also induced the expression of the surface-bound cytokine LIGHT and the chemokine receptor CCR9, both marker constitutively expressed by gut LP-resident T cells. In addition, we found that approximately 10% of the CD4(+) T lymphocytes isolated from the LP of patients undergoing bariatric surgery contain T cells that spontaneously secrete a cytokine pattern consistent with that from CD46-activated T cells. These data suggest that CD46-induced Tregs might play a role in intestinal immune homeostasis where they could dampen unwanted effector T cell responses through local IL-10/granzyme B production.