Invariant Vα14+ NKT cells participate in the early response to enteric Listeria monocytogenes infection

Invariant V alpha 14(+) NKT cells are a specialized CD1-reactive T cell subset implicated in innate and adaptive immunity. We assessed whether V alpha 14(+) NKT cells participated in the immune response against enteric Listeria monocytogenes infection in vivo. Using CD1d tetramers loaded with the synthetic lipid a-galactosylceramide (CD1d/alpha GC), we found that splenic and hepatic V alpha 14(+) NKT cells in C57BL/6 mice were early producers of IFN-gamma (but not IL-4) after L monocytogenes infection. Adoptive transfer of V alpha 14(+) NKT cells derived from TCR alpha degrees V alpha 14-J alpha 18 transgenic (TCR alpha degrees V alpha 14Tg) mice into alymphoid Rag degrees gamma(c)degrees mice demonstrated that V alpha 14(+) NKT cells were capable of providing early protection against enteric L monocytogenes infection with systemic production of IFN-gamma and reduction of the bacterial burden in the liver and spleen. Rechallenge experiments demonstrated that previously immunized wild-type and J alpha 18 degrees mice, but not TCR alpha degrees or TCR alpha degrees V alpha 14Tg mice, were able to mount adaptive responses to L. monocytogenes. These data demonstrate that V alpha 14(+) NKT cells are able to participate in the early response against enteric L monocytogenes through amplification of IFN-gamma production, but are not essential for, nor capable of, mediating memory responses required to sterilize the host.