Expression of KLRG1 on subpopulations of lymphocytes in the peripheral blood of patients with locally advanced nasopharyngeal carcinoma and prognostic analysis

Objective We aimed to investigate the relationship between the expression of killer cell lectin like receptor G1 (KLRG1) in peripheral blood lymphocytes, and the clinical characteristics and prognosis in patients with locally advanced nasopharyngeal carcinoma (NPC), and to dynamically evaluate the changes of KLRG1 expression after treatment. Methods A total of 82 patients with locally advanced NPC and 44 healthy individuals were recruited in this study. The expression of KLRG1 on T, natural killer, and natural killer T cells in peripheral blood mononuclear cells (PBMCs) was detected by flow cytometry. Its relationship with clinical characteristics and prognosis of patients, as well as changes in KLRG1 expression in PBMCs after treatment, were investigated. Results The expression of KLRG1 in CD8 + T cells in PBMCs of NPC patients was 46.50 (29.10, 69.80)%, significantly higher than 32.50 (17.38, 61.00) % in healthy controls ( Z  = −2.290, p  = 0.022). The expression of KLRG1 in CD3 + CD56 + natural killer T cells in PBMCs of patients was 29.50 (6.21, 78.00) %, significantly higher than 1.47 (0.62, 8.88)% in healthy controls ( Z  = −5.371, p  < 0.001). The expression levels of KLRG1(+)CD8 + T cells in PBMCs of patients were higher in the age ≥50 years ( Z  = −3.413, p  < 0.001), pathology of keratinizing squamous cell carcinoma ( H  = 10.541, p  = 0.005, and EGFR(+) groups ( Z  = −2.006, p  = 0.043). Patients with higher KLRG1(+) expression in CD8 + T cells had a lower progression‐free survival ( p  = 0.029) and a lower distant metastasis‐free survival ( p  = 0.023). KLRG1 expression on T cells increased after radiotherapy. Conclusion KLRG1 can be harnessed as a potential target in designing novel therapy to encompass a broader range of NPC patients.