CD38 identifies pre-activated CD8+ T cells which can be reinvigorated by anti-PD-1 blockade in human lung cancer

Background CD38 has been observed expressing in activated T cells, while the features and functions of CD38+ T cells in human NSCLC are still unclear. Methods Here we uncovered the correlation between CD38 expression and survival and immune infiltration levels in tumor of NSCLC. Then, we collected samples from 51 NSCLC patients to study the biological feature and response to anti-PD-1 of tumor-infiltrating CD38+ CD8+ T cells in vitro. Results We found CD38 expression correlated with the survival and immune infiltration levels of NSCLC. It is interesting that CD38+ CD8+ T cells enriched in the tumors expressed higher level of cytotoxic molecule, cytokines and PD-1 than CD38− CD8+ T cells. Moreover, PD-1+ subset in tumor-infiltrating CD38+ CD8+ T cells expressed higher level of activated markers than PD-1+ CD38− CD8+ T cells. Next, we found tumor-infiltrating CD38+ CD8+ T cells expressed higher level of CD103, IFN-γ, TNF-α and perforin than CD38− CD8+ T cells when were reactivated in vitro. Finally, we observed that CD38+ CD8+ T cells isolated from tumors could be reinvigorated by anti-PD-1 in vitro. Conclusions Our findings demonstrate that CD38 expression defines a subset of CD8+ T cells enriched in tumors of NSCLC which have paradoxical phenotypes and response to anti-PD-1. Our results suggest a pre-priming of these cells is may exist in tumor and consequentially facilitate it acquiring both anti-tumor potency and exhausted phenotype which can be reinvigorated by PD-1 blockade.