Prevention of mortality by in vivo depletion of alpha beta T cells in murine lethal listeriosis and involvement of gamma delta 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 alpha beta T cells by administration of anti-TCR beta mAb (H57-597) protected recipient mice from acute mortality and converted lethal listeriosis to sublethal infection. Furthermore, our findings suggested that gamma delta T cells were not involved in the liver necrosis in this condition. After depletion of alpha beta T cells, the number of bacteria decreased gradually to the limit for their detection (10(2) CFU) in 4 wks. Depletion of both alpha beta T cells and gamma delta T cells by administration of anti-TCR beta mAb (H57-597) and anti-TCR delta mAb (3A10) resulted in increased multiplication and persistent presence of bacteria in the liver and spleen. These findings suggest that gamma delta T cells play a significant protective role during infection in mice depleted of alpha beta T cells. In these mice, gamma delta T cells appeared with a peak on day 13 in the liver and on day 20 in the lymph nodes. No increase of gamma delta T cells in the spleen was observed throughout the course of infection.