The CD8α–PILRα interaction maintains CD8 <sup>+</sup> T cell quiescence
Linghua Zheng, Xue Han, Sheng Yao, Yuwen Zhu, John D. Klement, Shirley Wu, Lan Ji, Gefeng Zhu, Xiaoxiao Cheng, Zuzana Tobiásová, Weiwei Yu, Baozhu Huang, Matthew D. Vesely, Jun Wang, Jianping Zhang, Edward Quinlan, Lieping Chen
Abstract
T cell quiescence is essential for maintaining a broad repertoire against a large pool of diverse antigens from microbes and tumors, but the underlying molecular mechanisms remain largely unknown. We show here that CD8α is critical for the maintenance of CD8 + T cells in a physiologically quiescent state in peripheral lymphoid organs. Upon inducible deletion of CD8α, both naïve and memory CD8 + T cells spontaneously acquired activation phenotypes and subsequently died without exposure to specific antigens. PILRα was identified as a ligand for CD8α in both mice and humans, and disruption of this interaction was able to break CD8 + T cell quiescence. Thus, peripheral T cell pool size is actively maintained by the CD8α–PILRα interaction in the absence of antigen exposure.