IFN-γ-Inducible Chemokines Enhance Adaptive Immunity and Colitis

T helper type 1 (Th1) cells secreting interferon-γ (IFN-γ) have been closely associated with Crohn's disease (CD). Monokine-induced by IFN-γ (MIG), IFN-γ-inducible T cell α chemoattractant (I-TAC), and IFN-γ-inducible protein-10 (IP-10), are chemokines that bind CXCR3 and mediate the chemotaxis of leukocytes. IP-10, MIG, and CXCR3 have been shown to be expressed at sites of CD. The current study stems from our recent findings that IP-10, MIG, and I-TAC significantly contribute to the development of Th1-mediated inflammatory responses. To better understand the role of CXCR3 interactions during CD, we characterized the effects of IP-10, MIG, I-TAC, and CXCR3⁺ T cells on mucosal immune responses. IP-10, MIG, and I-TAC significantly enhanced antigen-specific serum and mucosal antibodies through Th1-mediated events and CD28 modulation. Additionally, the adoptive transfer of naive CXCR3⁺ T cells and CD4⁺CD45RB^HI to T cell receptor β (TCRβ)× δ^-/- mice resulted in the onset of murine colitis. Taken together, these studies suggest that IP-10, MIG, I-TAC, and CXCR3 interactions are involved in mucosal immune responses required for the induction of CD.