CD160 Signaling Is Essential for CD8+ T Cell Memory Formation via Upregulation of 4-1BB

A better understanding of the regulatory mechanisms governing the development of memory CD8(+) T cells could provide instructive insights into vaccination strategies and T cell-based immunotherapies. In this article, we showed that CD160 surface protein is required for CD8(+) T cell memory formation. In the response to acute lymphocytic choriomeningitis virus infection in a mouse model, CD160 ablation resulted in the failure of the development of all three memory CD8(+) T cell subsets (central, effective, and tissue-resident memory), concomitant with a skewed differentiation into short-lived effector T cells. Such memory-related defect was manifested by a diminished protection from viral rechallenge. Mechanistically, CD160 deficiency led to downregulation of 4-1BB in activated CD8(+) T cells, which contributes to the impaired cell survival and decreased respiratory capacity. The nexus between CD160 and 4-1BB was substantiated by the observation that ectopic introduction of 4-1BB was able to largely complement the loss of CD160 in memory CD8(+) T cell development. Collectively, our studies discovered that CD160, once thought to be a coinhibitor of T cell signaling, is an essential promoter of memory CD8(+) T cell development via activation of the costimulatory molecule 4-1BB.