γδ T cells mitigate the organ injury and mortality of sepsis

Sepsis is a difficult condition to treat and is associated with a high mortality rate. Sepsis is known to cause a marked depletion of lymphocytes, although the function of different lymphocyte subsets in the response to sepsis is unclear. γδ T cells are found largely in epithelial-rich tissues, and previous studies of γδ T cells in models of sepsis have yielded divergent results. In the present study, we examined the function of γδ T cells during sepsis in mice using cecal ligation and puncture (CLP). Mice deficient in γδ T cells had decreased survival times and increased tissue damage after CLP compared with wild-type mice. Furthermore, bacterial load was increased in γδ T cell-deficient mice, yet antibiotic treatment did not change mortality. Additionally, we found that recruitment of neutrophils and myeloid suppressor cells to the site of infection was diminished in γδ T cell-deficient mice. Finally, we found that circulating levels of IFN-γ were increased, and systemic levels of IL-10 were decreased in γδ T cell-deficient mice after CLP compared with wild-type mice. γδ T cell-deficient mice also had increased intestinal permeability after CLP compared with wild-type mice. Neutralization of IFN-γ abrogated the increase in intestinal permeability in γδ T cell-deficient mice. The intestines taken from γδ T cell-deficient mice had decreased myeloperoxidase yet had increased tissue damage as compared with wild-type mice. Collectively, our data suggest that γδ T cells modulate the response to sepsis and may be a potential therapeutic target.