Prevention of Mortality by in vivo Depletion of αβ T Cells in Murine Lethal Listeriosis and involvement of γδ T Cells in Bacterial Elimination

We previously demonstrated that in murine lethal listeriosis, death is mainly due to massive liver necrosis. In the present study we found that in vivo depletion of αβ T cells by administration of anti-TCR β mAb (H57-597) protected recipient mice from acute mortality and converted lethal listeriosis to sublethal infection. Furthermore, our findings suggested that γδ T cells were not involved in the liver necrosis in this condition. After depletion of αβ T cells, the number of bacteria decreased gradually to the limit for their detection (10² CFU) in 4 wks. Depletion of both αβ T cells and γδ T cells by administration of anti-TCR β mAb (H57-597) and anti-TCR δ mAb (3A10) resulted in increased multiplication and persistent presence of bacteria in the liver and spleen. These findings suggest that γδ T cells play a significant protective role during infection in mice depleted of αβ T cells. In these mice, γδ T cells appeared with a peak on day 13 in the liver and on day 20 in the lymph nodes. No increase of γδ T cells in the spleen was observed throughout the course of infection.