Phenotypic and functional exhaustion of circulating CD3⁺CD56⁺ NKT-like cells in colorectal cancer patients

CD3+CD56+ NKT-like cells are crucial to antitumor immune surveillance and defense. However, research on circulating NKT-like cells in colorectal cancer (CRC) patients is limited. This investigation selected 113 patients diagnosed with primary CRC for preoperative peripheral blood collection. The blood from 106 healthy donors at the physical examination center was acquired as a healthy control (HC). The distribution of lymphocyte subsets, immunophenotype, and functional characteristics of NKT-like cells was comprehensively evaluated. Compared to HC, primary CRC patients had considerably fewer peripheral NKT-like cells in frequency and absolute quantity, and the fraction of NKT-like cells was further reduced in patients with vascular invasion compared to those without. The NKT-like cells in CRC patients had a reduced fraction of the activating receptor CD16, up-regulated expression of inhibitory receptors LAG-3 and NKG2A, impaired production of TNF-alpha and IFN-gamma, as well as degranulation capacity. Moreover, the increased frequency of NKG2A+ NKT-like cells and the decreased expression of activation-related molecules were significantly correlated with tumor progression. In detail, NKG2A+ NKT-like cells indicated increased PD-1 and Tim-3 and reduced TNF-alpha than NKG2A- subgroup. Blocking NKG2A in vitro restored cytokine secretion capacity in NKT-like cells from CRC patients. Altogether, this research revealed that circulating NKT-like cells in CRC patients exhibited suppressive phenotype and functional impairment, which was more pronounced in NKG2A+ NKT-like cells. These findings suggest that NKG2A blockade may restore anti-tumor effector function in NKT-like cells, which provides a potential target for immunotherapy in CRC patients.