Interleukin-7 receptor (IL-7R) α-deficient mice have small numbers of B cells and αβT cells in periphery, they totally lack γδT cells. In addition, the V-J recombination and transcription of TCRγ genes is also severely impaired in IL-7Rα-deficient mice. Stat5, a signaling molecule of the IL-7R, induces germline transcription in the TCRγ locus, and promotes V-J recombination and γδT cell development. However, the roles for IL-7R signaling pathway in thymic or extrathymic γδT cell development are largely unknown.

To clarify the role of the IL-7 receptor in proliferation and survival of γδT cells, we introduced the TCR γδ transgene, V_γ2/Vδ₅, into IL-7Rα-deficient mice, and investigated the development of γδT cells.

We found that V_γ2/Vδ₅ transgene restored γδT cells in the epithelium of the small intestine (IEL) but not in the thymus and the spleen. Further addition of a bcl-2 transgene resulted in partial recovery of γδT cells in the thymus and the spleen of these mice.

Taken together, this study revealed that the IL-7Rα is indispensable for proliferation and survival mainly in thymic γδT cell development.