Localization of NK1.1+ invariant Vα19 TCR+ cells in the liver with potential to promptly respond to TCR stimulation

Previously, we found that more than a half of the NK1.1+ T cell lines prepared from CD1−/− livers expressed invariant Vα19-Jα33 TCR α chains. Over-expression of the invariant Vα19-Jα33 TCR α transgene (Tg) with a natural TCR α promoter and an enhancer in mice induced the development of NK1.1+ T cells (Vα19 NKT cells) in the lymphoid organs, especially in the liver. Preferential usage of the Vα19 Tg by NKT cells in the transgenic mouse livers was indirectly indicated by the observation that few NK1.1+ TCRαβ+ cells of the Vα19 Tg livers were stained with a cocktail of anti-TCR Vα antibodies in the FACS analysis. Upon invariant TCR engagement in vivo following injection of mice with anti-CD3 antibody, NKT cells of the Tg mouse livers as well as spleens promptly produced immunoregulatory cytokines such as IL-4 and IFN-γ and altered surface receptor expression. Collectively, localization of Vα19 NKT cells in the liver is suggested that are ready to immediately response against antigen stimulation.