Human Vγ2Vδ2 T Cells Augment Migration-Inhibitory Factor Secretion and Counteract the Inhibitory Effect of Glucocorticoids on IL-1β and TNF-α Production

Abstract In immune cells, proinflammatory cytokine gene expression is regulated by glucocorticoids, whereas migration-inhibitory factor (MIF), a pleiotropic cytokine, has the unique property of counteracting the inhibitory effect of glucocorticoids on TNF-α and IL-1β secretion. A few lines of evidence suggest that γδ T cells play an important role in immunoregulation. However, it is unknown whether human γδ T cells participate in regulating MIF secretion, and how γδ T cells, glucocorticoids, and cytokines converge to give a unified physiological response. In this study, we demonstrate that human Vγ2Vδ2 T cells augment MIF secretion. Remarkably, these Vγ2Vδ2 T cells, functioning similarly to MIF in part, counteracted inhibition of dexamethasone on production of IL-1β and TNF-α. SCID mice reconstituted with human PBMC that were mock depleted of Vδ2 T cells and repeatedly infected with lethal dose of Escherichia coli had shorter survival time than those reconstituted with PBMC that were depleted of Vδ2 T cells. Thus, human Vγ2Vδ2 T cells are likely to play broad-spectrum roles in immunoregulation and immunopathology by influencing MIF secretion and the immunomodulatory function of glucocorticoids.