Thus, in primed CD8+ T cells, CD27 signaling contributes to survival by upregulating anti-apoptotic Bcl-2 family members as well as Pim-1, a serine/threonine kinase capable of sustaining survival of rapidly proliferating cells 4. Given the broad distribution of CD27, it check details is

not surprising that CD27 is also expressed by γδ T cells. Furthermore, studies with human γδ T cells showed that expression of CD27 marks stages of cellular differentiation. Naïve and central memory cells within the Vγ9Vδ2+ subset, which is predominant in the blood, express CD27 on the cell surface, whereas effector memory cells within this subset lack CD27 expression 5; however, there has been little information about the functional role of CD27 expressed by γδ T cells. In three related studies, the research team headed by Bruno Silva-Santos now has filled much of this knowledge gap 6–8. Investigating Talazoparib ic50 the development of γδ T cells in mice, Ribot and colleagues found that CD27 already functions as a regulator of differentiation in the thymus 6, where it induces expression of the lymphotoxin-β receptor as well as genes associated with transconditioning and IFN-γ production. Thus, γδ TCR+ thymocytes that express CD27 develop into producers of

IFN-γ, whereas those that do not express CD27 are unable to generate IFN-γ but produce IL-17 instead 6. This complements an earlier report from Chien’s group indicating Neratinib chemical structure that TCR engagement determines whether γδ thymocytes develop into IFN-γ or IL-17 producers 9. Presumably, signals through the TCR and CD27 somehow synergize in determining γδ T-cell differentiation. Importantly, the correlation between expression of cytokines and CD27 was found to be stable, extending to mature γδ T cells in the periphery 6, and was maintained even during infection 7. As pointed out by the authors 6, this lack of plasticity in CD27+ cells distinguishes γδ T cells from αβ T cells and B cells, encouraging the notion of CD27+/− γδ T-cell functional subsets. Continuing their studies in mouse models, Ribot and colleagues

next examined the role of CD27 in γδ T-cell responses to infections with herpes virus and malaria 7. Here, in IFN-γ-producing CD27+ peripheral γδ T cells, CD27 costimulation was seen to synergize with the γδ TCR, providing survival and proliferative signals that determined the extent of in vivo γδ T-cell expansion in response to these infections. In sharp contrast, IL-17-producing CD27− γδ T cells during malaria infection relied on TLR/MyD88-mediated innate immune signals, revealing an entirely different TCR-independent pathway of immune engagement, at least in this γδ T-cell functional subset. Finally, in this issue of European Journal of Immunology, Silva-Santos’s group 8 examines the functional role of CD27 expressed by Vγ9Vδ2+ human peripheral blood γδ T lymphocytes.