Response of Circulating Regulatory T Cells to Chemoradiotherapy of Lung Cancer and Brachytherapy for Prostate Cancer

Purpose: To evaluate the dynamics of circulating regulatory T cells (Treg) and changes in their adenosine-dependent functional suppressor activity during chemoradiotherapy of lung cancer (LC) and brachytherapy for prostate cancer (PC). Material and methods: The study included 19 patients with LC (38 cytometric peripheral blood tests at three control points of chemoradiotherapy) and 23 patients with PC (66 cytometric tests at four control points of brachytherapy). Two control groups were used in the analysis: the main group (40 practically healthy people, blood donors: 22 women and 18 men) to assess the initial level of Treg cells in LC; and an additional group (14 practically healthy people, blood donors) to study the functional activity of Treg cells in patients with LC and PC. The content of Treg cells in patients at the onset of PC was compared with a subgroup of men in the main control group (n=18). Statistical data processing was performed using the Mann–Whitney U-test (pairwise comparison) and the Kruskal‒Wallis criterion (multiple comparison). Results: Patients with LC and PC before treatment showed a statistically significant increase in the level of circulating Treg cells compared with control values (p0.05). The level of CD39 expression on Treg cells remained stable during treatment with LC and PC and corresponded to the control values (p>0.05). Conclusion: The high content of Treg cells after chemoradiotherapy LC and PC brachytherapy indicates the persistence of immunosuppression at the systemic level, which negatively affects the results of treatment. The development of strategies for targeted modulation of Treg cells is necessary to increase the effectiveness of cancer therapy.