IL-12 drives the expression of the inhibitory receptor NKG2A on human tumor-reactive CD8 T cells

Blockade of NKG2A/HLA-E interaction is a promising strategy to unleash the anti-tumor response. Yet the regulation of NKG2A expression on CD8+ lymphocytes and the T cell anti-tumor response are still poorly understood. Here, by performing CITE-seq on human T cells derived from head and neck squamous cell carcinoma and colorectal cancer, we show that NKG2A expression is induced in tumor-infiltrating CD8+ T cells differentiating into cytotoxic, CD39+CD103+ double positive (DP) T cells. This developmental trajectory lead to TCR repertoire overlap between the NKG2A– and NKG2A+ DP CD8 T cells, suggesting shared antigen specificities. Mechanistically, IL-12 is essential for the expression of the NKG2A on naïve CD8+ T cells in a CD40/CD40L- dependent manner, in conjunction with TCR stimulation and increased TGF-β levels. Our study thus reveals that NKG2A is induced by IL-12 on human tumor-reactive CD8+ T cells exposed to a TGF-b-rich environment, highlighting an underappreciated immuno-regulatory feedback loop dependent on IL-12 stimulation.