The role of CD1d in the immune response against Listeria infection

To address the role of CD1d in mucosal immune regulation in bacterial infection, we infected CD1d KO mice with Listeria monocytogenes (Lm). A higher systemic bacterial burden associated with inflammatory lymphocytic infiltrations within the intestine was found in CD1d KO compared with wild type (WT) mice. Lm induced strong IFN-γ mRNA expression in the liver of WT and the intestine of CD1d KO mice, thus demonstrating the dual, opposing immune activities of IFN-γ in Lm infection that is dependent on CD1d and/or NKT cells. Analysis of hepatic T cell population demonstrated a reduction of NK1.1+TCRβ+ cells in both mice, followed by recovery only in WT mice. Last, the proportion of α4β1 integrin on lung lymphocytes from CD1d KO was dramatically increased compared with WT mice. Thus, the absence of CD1d resulted in increased susceptibility towards Listeria infection, induced changes in NKT cells, and increased trafficking of α4β1 molecule to inflamed lung.