Effect of fractionated radiotherapy of transplanted hepatocellular carcinoma on the splenic immune cells in mice / 中华放射医学与防护杂志

ABSTRACT

Objective To investigate the effect of fractionated radiotherapy on the immune system of mice with subcutaneously transplanted hepatocellular carcinoma.Methods Logarithmic growth of mouse hepatocellular carcinoma cells Hepa 1-6 were inoculated subcutaneously on the right side of C57BL/6 J mice (1×107 cells/mice).The tumor-bearing mice were randomly divided into control group (Ctrl) and irradiation group (IR),20 mice in each group.Additionally,10 healthy mice were set as normal control group.Local fractionated X-ray irradiation of 8 Gy×3 fraction was given to the subcutaneous tumors,and the dose rate was 0.883 Gy/min.At 7 and 14 d after irradiation,the tumor organ index,spleen organ index,spleen pathological changes,and splenic T lymphocyte subsets,B lymphocyte subsets,and NK cells were detected.Results Compared with Ctrl,at 7 and 14 d after irradiation,the tumor organ index decreased (t =4.649,26.34,P＜0.05),and the percentage of NK cells increased significantly (t =3.952,3.633,P＜0.05).The percentages of CD3+,CD4+,CD3+CD4+ lymphocytes and the ratio of CD4+/CD8+ lymphocyte decreased at 7 d after irradiation (t=3.193,3.656,3.219,2.641,P＜0.05),and the percentage of CD3+lymphocyte decreased at 14 d after irradiation (t =3.031,P＜0.05).But after irradiation,there were no significant changes in spleen organ index,B lymphocyte,CD3 + CD4+ lymphocyte and CD8 + lymphocyte.Conclusions Local hepatoma radiotherapy causes imbalance of lymphocytes in distal spleen of mice and hence reduces immunity,which provides a novel mechanism of radiological immunity damage.