Effect of ionizing irradiation on expressions of TLR4 and adaptor protein MyD88 in peritoneal macrophages of mice

Objective: To observe the effect of ionizing radiation on the expressions of TLR4 and adaptor protein MyD88 in mouse peritoneal macrophages in the Toll-mediated signal transduction pathways. Methods: 160 male Kunming white mice were randomly divided into 16 groups(ten each group): sham-irradiation and five groups after 4,8,16,24 and 48 h X-ray irradiation for time-course experiments; sham-irradiation and nine groups after 0.05,0.075,0.100,0.200,0.500,1.000,2.000,4.000,6.000 Gy irradiation for dose-effect experiments. Flow cytometry was used to detect the expressions of TLR4 and MyD88 after whole body irradiation (WBI) with X-rays. Results: Both of TLR4 and Myd88 expressed more than shamirradiation after 0.075 and 2.000 Gy WBI for 4 h,and the expressions of them reached the peak at 16 h or 4 h after WBI(P<0.05 or P<0.01) in time-course experiments. In dose-effect experiments, the expression levels of TLR4 and MyD88 increased gradually with the enhancement of X-rays irradiation dose, both of them reached the peak at 2.000 Gy WBI, and there was significant difference compared with sham-irradiation group(P<0.01). Conclusion: X-ray irradiation can increase the expressions of TLR4 and MyD88 in mouse peritoneal macrophages, promote the immune respose and start the adaptive immunity of mice. (authors)