IMMUNOBIOLOGY T-bet is required for optimal proinflammatory CD4 T-cell trafficking

Inflammatory responses are controlled by T helper 1 (Th1) lymphocytes. An im-portant function of this polarity is the ability of T cells to traffick appropriately in vivo. This differential trafficking is de-pendent upon the binding of P-selectin glycoprotein ligand-1 to P- and E-selectin on inflamed endothelium as well as the expression of specific chemokine recep-tors. Here we show that in the absence of T-box expressed in T cells (T-bet), selec-tive migration of T cells in vivo is com-pletely abrogated and that T-bet regulates the binding of CD4 T cells to P-selectin. T-bet is also required for the expression of the chemokine receptor CXCR3. Thus, T-bet controls Th1-cell migration to inflam-matory sites, which has fundamental con-sequences for the control of immunologic disease. (Blood. 2005;106:3432-3439) © 2005 by The American Society of Hematolog