Immunity to infections relies on clonal expansion of CD8+ T cells, their maintenance as effector CTLs, and their selection into a memory population. These processes rely on delivery of survival signals to activated CD8+ T cells. We here reveal the mechanism by which costimulatory CD27-CD70 interactions sustain survival of CD8+ effector T cells in infected tissue. By unbiased genome-wide gene expression analysis, we identified the Il2 gene as the most prominent CD27 target gene in murine CD8+ T cells. In vitro, CD27 directed IL-2 expression and promoted clonal expansion of primed CD8+ T cells exclusively by IL-2–dependent survival signaling. In mice intranasally infected with influenza virus, Cd27–/– CD8+ effector T cells displayed reduced IL-2 production, accompanied by impaired accumulation in lymphoid organs and in the lungs, which constitute the tissue effector site. Reconstitution of Cd27–/– CD8+ T cells with the IL2 gene restored their accumulation to wild-type levels in the lungs, but it did not rescue their accumulation in lymphoid organs. Competition experiments showed that the IL-2 produced under the control of CD27 supported effector CD8+ T cell survival in the lungs in an autocrine manner. We conclude that CD27 signaling directs the IL-2 production that is reportedly essential to sustain survival of virus-specific CTLs in nonlymphoid tissue.
Victor Peperzak, Yanling Xiao, Elise A.M. Veraar, Jannie Borst
The Editorial Board will only consider comments that are deemed relevant and of interest to readers. The Journal will not post data that have not been subjected to peer review; or a comment that is essentially a reiteration of another comment.