RESUMO
Objective:To observe the antagonism of dexamethasone on radiation bystander effect and its re-transmission in rabbit lymphocytes.Methods:The plasmas of 2 New Zealand rabbits which were irradiated with 6 MV X-ray was taken to prepare the first generation of conditioned medium; the plasmas of 2 unirradiated New Zealand rabbits were taken to prepare the first generation of unconditioned culture medium; The lymphocytes of 5 unirradiated New Zealand rabbits were extracted. The lymphocytes from 5 unirradiated New Zealand rabbits were cocultured with the first generation of unconditioned medium or conditioned medium. After abandoning the culture medium, the lymphocytes were cultured in conventional medium for 24 h. The second generation of unconditioned medium or conditioned medium was taken. The lymphocytes were treated with four medium with or without dexamethasone (1 μg/ml), and the apoptosis rate of lymphocytes was detected by flow cytometry.Results:With or without dexamethasone, the apoptosis rates of lymphocytes treated with the first generation of conditioned medium was significantly higher than that with the first generation of unconditioned medium [without dexamethasone: (21.09±1.60)% vs. (8.06±0.65)%, t = -30.182, P < 0.05; with dexamethasone: (14.96±1.80)% vs. (6.25±0.54)%, t = -16.404, P < 0.05]. Dexamethasone could reduce the apoptosis rates of lymphocytes treated with the first generation of unconditioned medium and the first generation of conditioned medium, and the differences were statistically significant (both P < 0.05). With or without dexamethasone, the apoptosis rates of lymphocytes treated with the second generation of conditioned medium was significantly higher than that with the second generation of unconditioned medium [without dexamethasone: (28.70±2.14)% vs. (12.38±0.67)%, t = -33.351, P < 0.05; with dexamethasone: (20.21±1.96)% vs. (12.53±1.25)%, t = -14.145, P < 0.05]. Dexamethasone could reduce the apoptosis rates of lymphocytes treated with the second generation of conditioned medium ( P < 0.05), but it could not reduce the apoptosis rate of lymphocytes treated with the second generation of unconditioned medium ( P > 0.05). Conclusion:Dexamethasone can antagonize the injury of lymphocytes by radiation bystander effect in vitro, reduce the apoptosis rate of lymphocytes, and can also antagonize the re-transmission of radiation bystander effect.