Effect of low dose X-ray irradiation on migration of human dendrite cells and underlying mechanism

Objective: To study the effect of low dose X-ray irradiation on the migration of human dendritic cells and its mechanism in vitro. Methods: The human peripheral blood mononuclear cells (PBMC) were separated and treated with rhGM-CSF and rhIL-4 in order to differentiate them to dendritic cells (DC) in vitro. To enhance cell maturation, 50 mg/L TNF-α was added into the medium at 5 d of culture. At 6 d of cell culture, DCs were radiated with X-rays of 0.05, 0.1, 0.2 and 0.5 Gy, respectively. At 8 d, the dendrite cells were collected for further analysis. The expressions of CC-Chemokine Receptor 7 (CCR7) mRNA and its protein were detected by RT-PCR and Western blot, respectively. Transwell culture inserts were used to measure the amount of migrated cells. Results: After 0.2 and 0.5 Gy radiation, the expression of CCR7 mRNA of DCs was remarkably increased(t = 14.72, 4.72, P < 0.05), but the expression of CCR7 protein in the DCs irradiated with 0.2 Gy was higher than that irradiated with other doses(t = 4.46, P < 0.05), meanwhile the amount of migrated DCs was obviously increased(t = 2.95, P < 0.05). Furthermore, DCs treated with anti-CCR7 monoclone antibody decreased the ability of radiation-induced migration(t = 4.63-8.96, P < 0.05). Conclusions: 0.2 Gy X-ray irradiation significantly can enhance the migration ability of DCs in vitro, which may be correlated with the increase of CCR7 expression. (authors)