Objective To explore the adverse effects of radon and its daughters on lymphocytes in thymus, spleen, peripheral blood (PB), bone marrow (BM), and provide experimental data for mechanistic investigation on radon-induced immune damage in rats.
Methods Fifteen male Wistar rats were divided to three groups with 5 rats in each group:1 control group and 2 exposure groups. The exposed rats were placed in a HD-3 multifunction ecological radon chamber at a cumulative radiation dose of 200 or 400 working level months (WLM). At the end of the exposure, the spleen and thymus of the rats were aseptically excised, and PB & BM were collected to obtain single cells. The total number and proportion of cells in BM and PB were counted. The level of reactive oxygen species (ROS), intracellular free calcium concentration, mitochondrial membrane potential (MMP), cell cycle, and the apoptosis in lymphocytes were also detected by fluorescence probe.
Results The 200 WLM radon exposure resulted in a statistically significant increase of lymphocytes in the PB in comparison with the control group(6.84& #177;1.40)& #215;109/L vs. (3.34& #177;1.10)& #215;109/L, P< 0.01; the same changes were found in the BM of the two exposure groups. The level of ROS of thymus lymphocytes in the 200 WLM group was significantly higher than that in the control group (P< 0.01). In the same group, the MMP of lymphocytes in BM and PB were significantly lower, and the intracellular Ca2+ concentration of lymphocytes of spleen and thymus were significantly higher than the corresponding indices of the controls (P< 0.01). The G0/G1 phase of thymocytes from the 200 WLM group was reduced and the S phase was prolonged; opposite results were observed in the splenocytes with baseline of the controls. The apoptotic rate of thymocytes in the 200 WLM group was (1.63& #177;0.46)%, significantly higher than that in the control group(0.69& #177;0.64)%, P< 0.05; but the same effect was not observed in the 400 WLM group.
Conclusion Radon and its daughters may cause toxic effects on immune cells and immune function of rats.
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