Objective: To investigate the effect of single large fraction radiotherapy on dendritic cells activation to T cell in vitro. Methods: Peripheral blood PBMC were collected from hepatocellular carcinoma patients. Then, DC was obtained in vitro under the stimulation of cytokines. HepG2 cells were irradiated at 15Gy/1f and 5Gy/3f, respectively. Tumor associated antigens were obtained by centrifugation. The changes of cell phenotypes of HLA-DR, CD40, CD80, CD83 and CD86 by 15Gy/1f TAA DC and 5Gy/3f TAA DC were detected with flow cytometry. The concentration of cytokines IL-12p70, IL-1β, IL-6 and TNF-α secreted by 15Gy/1f TAA DC and 5Gy/3f TAA DC were detected using ELISA. Intracellular staining was used to detect the activation of specific T cells by DC loaded with 15Gy/1f and 5Gy/3f TAA. MTT assay was used to detect the killing activity of the above activated T cells on HepG2 cells. Results: The cell phenotypes of HLA-DR, CD40, CD80, CD83 and CD86 of DC loaded with 15Gy/1f TAA were all higher than those of 5Gy/3f group (P<0.05). The concentration of cytokines IL-12p70 and IL-6 secreted by DC loaded with 15Gy/1f TAA were higher than those in the 5Gy/3f group. Intracellular staining results showed that DC loaded with 15Gy/1f TAA tended to stimulate CD4+ T cells[(0.392±0.187)% vs (0.315±0.118)%] and CD8+ T cells[(0.362±0.159)% vs (0.119±0.090)%] to secret IFN-γ than 5Gy/3f group (P<0.05). MTT results showed that T cells activated by 15Gy/1f group had stronger killing activity on HepG2 cells than 5Gy/3f group (P<0.05). Conclusion: Single high fractionation radiotherapy can stimulate the activation of specific T cells by DC. This provides a theoretical basis for the treatment of liver cancer in the future.
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