IL-12 and IL-27 Promote CD39 Expression on CD8+ T Cells and Differentially Regulate the CD39+CD8+ T Cell Phenotype

Abstract

Tumor-specific CD8+ T cells are critical components of antitumor immunity; however, factors that modulate their phenotype and function have not been completely elucidated. Cytokines IL-12 and IL-27 have recognized roles in promoting CD8+ T cells’ effector function and mediated antitumor responses. Tumor-specific CD8+ tumor-infiltrating lymphocytes (TILs) can be identified based on surface expression of CD39, whereas bystander CD8+ TILs do not express this enzyme. It is currently unclear how and why tumor-specific CD8+ T cells uniquely express CD39. Given the important roles of IL-12 and IL-27 in promoting CD8+ T cell functionality, we investigated whether these cytokines could modulate CD39 expression on these cells. Using in vitro stimulation assays, we identified that murine splenic CD8+ T cells differentially upregulate CD39 in the presence of IL-12 and IL-27. Subsequently, we assessed the exhaustion profile of IL-12– and IL-27–induced CD39+CD8+ T cells. Despite the greatest frequency of exhausted CD39+CD8+ T cells after activation with IL-12, as demonstrated by the coexpression of TIM-3+PD-1+LAG-3+ and reduced degranulation capacity, these cells retained the ability to produce IFN-γ. IL-27–induced CD39+CD8+ T cells expressed PD-1 but did not exhibit a terminally exhausted phenotype. IL-27 was able to attenuate IL-12–mediated inhibitory receptor expression on CD39+CD8+ T cells but did not rescue degranulation ability. Using an immunogenic neuro-2a mouse model, inhibiting IL-12 activity reduced CD39+CD8+ TIL frequency compared with controls without changing the overall CD8+ TIL frequency. These results provide insight into immune regulators of CD39 expression on CD8+ T cells and further highlight the differential impact of CD39-inducing factors on the phenotype and effector functions of CD8+ T cells.

Case Report: Genetic and immune microenvironmental characteristics of a rectal cancer patient with MSS/PD-L1-negative recurrent hepatopulmonary metastasis who achieved complete remission after treatment with PD-1 inhibitor

“…Meanwhile, CD4 + T cells could promote the recruitment and activation of CD8 + T cells, macrophages and natural killer (CD57 + ) cells to enhance the antitumor effect. Studies revealed CD39 could serve as a marker for identification of tumor-specific T cells and CD39 + CD8 + , CD39 + CD4 + TILs were found to be beneficial for antitumor activity (26,27). Interestingly, FOXP3 + T cells are usually regarded as suppressive T cells in many cancers except CRC, in which FOXP3 + T cells indicated better prognosis in some studies (12)(13)(14).…”