γδ T cell homeostasis is established in competition with αβ T cells and NK cells

gamma delta T cells are a diverse population of lymphocytes that play an important role in immune regulation. The size of the gamma delta T cell pool is tightly regulated, comprising only 1-10% of total lymphoid T cells in mice and humans. We examined the homeostatic regulation of gamma delta T cells using a model of lymphopenia-incluced homeostatic expansion. We found that IL-15 and, to a lesser extent, IL-7 play an important role in lymphoid gamma delta T cell homeostasis. Moreover, gamma delta T cell homeostatic expansion was limited not only by gamma delta T cells themselves but also by natural killer cells and alpha beta T cells. Our results suggest that CD8(+) alpha beta T cells are the most potent inhibitors of gamma delta T cell homeostasis and exert their effect by competing for IL-15.