Tespa1 deficiency reduces the antitumour immune response by decreasing CD8 + T cell activity in a mouse Lewis lung cancer model.

Thymocyte-expressed, positive selection-associated 1 (Tespa1) is a key molecule in T-cell development and has been linked to immune diseases. However, its role in antitumour CD8T cell immunity remains unclear. Here, we demonstrated that Tespa1 plays an important role in antitumour CD8T cell immunity. First, compared with wild-type (WT) mice, Lewis lung cancer cells grew faster in Tespa1 knockout (Tespa1) mice, with reduced apoptosis, and decreased CD8T cells in peripheral blood and tumor tissues. Second, the proportion of CD8T and Th1 cells in the splenocytes of Tespa1 mice was lower than that in WT mice. Third, Tespa1 CD8 tumor-infiltrating lymphocytes (TILs) showed weakened proliferation, invasion, cytotoxicity, and protein expression of IL-2 signalling pathway components compared to WT CD8TILs. Furthermore, PD-1 expression in CD8TILs was higher in Tespa1 than in WT mice. Lastly, CD8TILs in WT mice improved the antitumour ability of Tespa1 mice. In conclusion, these findings suggest that Tespa1 plays a critical role in the tumor immune system by regulating CD8T cells.