Objective To investigate the expression and regulation of programmed cell death protein 1 (PD1), B lymphocyte and T lymphocyte attenuator (BTLA) in peripheral blood of patients with non-small cell lung cancer (NSCLC); to examine the correlation of the mRNA levels between PD and BTLA in NSCLC. Methods Flow cytometry was used to detect the expression of PD1 and BTLA on the surfaces of CD8⁺ T cells and γδ⁺ T cells in the peripheral blood samples collected from 32 in-patients with stage IV NSCLC and 30 healthy individuals. We compared the expression of PD1 and BTLA on the surfaces of γδ⁺ T cells in the NSCLC patients with bone metastasis before and after the treatment of zoledronic acid. The correlations of PD1 and BTLA, as well as their ligands were analyzed using Pearson correlation analysis with the cBioPortal data platform. Results The frequency of PD1 on the surfaces of CD8⁺ T cells was significantly higher than that of the γδT cells in both healthy controls (t=2.324, P=0.024) and NSCLC patients（t=2.498, P=0.015). The frequency of PD1 on CD8⁺ T cells, rather than on γδ⁺ T cells, was significantly upregulated in advanced NSCLC patients compared with that in healthy controls (t=4.829, P<0.001). The PD1⁺ BTLA⁺γδT cells of the healthy controls were significantly lower than that of the NSCLC patients (t=2.422, P=0.0185). No differences in percentage of PD1⁺γδ⁺ and BTLA⁺γδ⁺ T cells were observed in 7 NSCLC patients with bone metastasis before and after zoledronic acid treatment. PD1 was positively correlated with BTLA in both lung adenocarcinoma (r=0.54; P<0.05) and lung squamous cell carcinoma (r=0.78; P<0.05). Conclusions The upregulation of co-inhibitory molecules occurs on the surfaces of both CD8⁺ T cells and γδT cells in advanced NSCLC, suggesting that these molecules were involved in regulating the inactivation of CD8⁺ T cells and γδ⁺ T cells, immune escape and tumor invasion.

Key words: CD8⁺ T cell, γδ T cell;, programmed cell death protein 1, B and T lymphocyte attenuator, non-small cell lung cancer

Funding: Fund supported by the Healthcare Technology Plan of Zhejiang Provincial Health Bureau No(2016KYB292);and the Technology Plan of Science and Technology Bureau of Jiaxing, Zhejiang province No(2016AY23054)