The Effects Of Low Dose X Ray Irradiation On The Functions Of Human Dendritic Cells Derived From The Peripheral Blood

ObjectiveTo explore the effects of low dose X ray irradiation on the abilities of apoptosis,maturation, antigen presentation, activating T cells to kill lung cancer A549cellsand IL-12secretion of human Dendritic cells in vitro.MethodsThe human peripheral blood mononuclear cells (PBMC),were separated andcultured and treated with rhGM-CSF and rhIL-4. LIN antibody was used for cellspurification. HLA-DR and CD11c antibody were used for cells identification ofhuman dendritic cells (DCs) in vitro. The DCs were divided into3groups. GroupA: DCs were radiated separately in the dose of0.05Gy,0.1Gy,0.2Gy and0.5Gy after cultured for2days; Group B: DCs were radiated separately in the doseof0.05Gy,0.1Gy,0.2Gy and0.5Gy after cultured for6days; Group C wascontrol group which DCs were cultured and without irradiation Anti-Annexin-VFITC and PI staining were used for detect the apoptosis after radiated24and48h. Flow cytometry was used for surface maker CD80and CD83examination,CCK-8(cell counting kit-8) was used for the counting of T cells and evaluationthe antigen presentation ability of DC (mixed lymphocyte reaction, MLR). MTTwas used for the counting of A549cells, enzyme-linked immunoassay (ELISA)was used for the testing of IL-12and IFN-γconcentration. Results1. According to our recommended method，cultured DC had high maturity andpurity, and can be used for the experiments.2. The apoptosis rate of DCs both in group A and group B increased remarkablycompare with control group after DCs radiated by0.5Gy at the8th days forcultured （in group A24h,48h t value were2.88,2.54; group B were2.97,3.73seperately, P<0.05）.3. After0.2Gy、0.5Gy irradiation, CD80and CD83levels in the group A werelower but group B were higher than control group（P<0.05）at the8th day forcultured.4. After radiated at the dosed of0.2Gy,0.5Gy, the antigene presention abilityof DCs in group A was remarkably decreased (t=2.79,3.71, P<0.05), but groupB was significantly increased than control (t=3.60,,3.11, P<0.05). Meanwhile,the levels of IL-12in group A was dramatically decreased (t=4.44,6.93, P<0.05)and group B was obviously increased than control (t=3.51,4.12，P<0.05).5. Compare with the control group, the ability of the DCs activated T cells to killlung carcinoma A549cells in group A was decreased (t=2.89,2.91, P<0.05),but group B was increased after DCs were radiated at the dose of0.2Gy and0.5Gy (t=2.91,2.82, P<0.05). Meanwhile，the ability of DC to induce T cellssecretion IFN-γ in group A was significantly decrease, and in group B wasobviously increased (P<0.05). When DCs were radiated at the dose of0.05Gyand0.1Gy compare with control, the abilities of the DCs activated T cells to killA549cells and to secret IFN-γ had no markedly difference in both group A andgroup B.ConclusionsThe irradiation at the dose of0.5Gy would induce the DC’s apoptosis. When DCs were cultured for2days (early stage, group A), the irradiation at the doseof0.2Gy and0.5Gy would decrease DC’s abilities of maturity, antigenpresentation, IL-12secretion, activation T cells to secret INF-γ and to kill A549cells. But when DCs were cultured for6days (later stage, group B), theirradiation at the dose of0.2Gy and0.5Gy would increase DC’s abilities ofmaturity, antigen presentation, IL-12secretion, activation T cells to secret INF-γand to kill A549cells. These results might be useful for the explorsion the effectsof lower dose radiation on human immunity system and it’s mechnism.