The protective role of T‐cell receptor Vγ1 + T cells in primary infection with Listeria monocytogenes

We have previously reported that the T‐cell receptor (TCR) γδ + T cells increase in mice infected with an intracellular bacteria Listeria monocytogenes , and the cells predominantly express Vδ6 and Vγ1 genes. In this study, we used a monoclonal antibody (mAb) specific to TCR Vγ1 to estimate the frequency of Vγ1 + T cells and we discuss their significance in protection against L. monocytogenes . The spleen, liver and peritoneal exudate cells from mice intraperitoneally infected with L. monocytogenes were analysed by flow cytometry. In all the organs investigated, Vγ1 + cells increased predominantly among TCR γδ + T cells at an early phase (day 5–7) of the infection. To elucidate the significance of the Vγ1 + T cells in the protection against L. monocytogenes , mice were depleted of TCR Vγ1 + γδ T cells or all TCR γδ + T cells by intraperitoneal inoculation of anti‐Vγ1 mAb or anti‐pan TCR γδ mAb, respectively, before infection with L. monocytogenes . The bacterial growth in the spleen and the liver examined on day 5 after the infection increased significantly by the depletion of TCR Vγ1 + T cells. The numbers of L. monocytogenes in TCR Vγ1 + T‐cell‐depleted mice were nearly the same as in mice depleted of all TCR γδ + T cells. These results demonstrated that Vγ1 + T cells are the predominant population of γδ T cells in protection against L. monocytogenes at the early phase of the primary infection.