Invariant Vα14+ NKT Cells Participate in the Early Response to Enteric Listeria monocytogenes Infection

Abstract

Invariant Vα14+ NKT cells are a specialized CD1-reactive T cell subset implicated in innate and adaptive immunity. We assessed whether Vα14+ NKT cells participated in the immune response against enteric Listeria monocytogenes infection in vivo. Using CD1d tetramers loaded with the synthetic lipid α-galactosylceramide (CD1d/αGC), we found that splenic and hepatic Vα14+ NKT cells in C57BL/6 mice were early producers of IFN-γ (but not IL-4) after L. monocytogenes infection. Adoptive transfer of Vα14+ NKT cells derived from TCRα° Vα14-Jα18 transgenic (TCRα°Vα14Tg) mice into alymphoid Rag°γc° mice demonstrated that Vα14+ NKT cells were capable of providing early protection against enteric L. monocytogenes infection with systemic production of IFN-γ and reduction of the bacterial burden in the liver and spleen. Rechallenge experiments demonstrated that previously immunized wild-type and Jα18° mice, but not TCRα° or TCRα°Vα14Tg mice, were able to mount adaptive responses to L. monocytogenes. These data demonstrate that Vα14+ NKT cells are able to participate in the early response against enteric L. monocytogenes through amplification of IFN-γ production, but are not essential for, nor capable of, mediating memory responses required to sterilize the host.