Effects of multiple low dose radiation on spleen T lymphocyte subgroups in eight-week diabetic rats

Objective: To explore the changes of spleen lymphocyte subgroups in diabetic rats after multiple low dose radiation (LDR). Methods: The experiment was divided into normal control group, pure diabetes mellitus (DM) group, and DM plus different doses of irradiation groups (the irradiation doses were 0.025, 0.050 and 0.075 Gy, respectively). The diabetic rat model was induced by intraperitoneal injection of streptozotocin. After the diabetic rats were irradiated 15 times, the percentages of spleen CD4+ and CD8+ T cells and ratio of CD4+/CD8+ T cells were detected with flow cytometry on the fourth weekend. Results: The diabetic rats manifested obvious polydipsia, polyphagia, polyuria and weight loss. On the fourth weekend after irradiation, as compared with normal control group, the percentage of spleen CD4+ T cells increased significantly (P<0.01), and that of CD8+ T cells decreased significantly (P<0.01), and the ratio of CD4+/CD8+ T cells was increased significantly (P<0.01) in diabetic rats; but the changes of spleen lymphocyte subgroups were not significant in LDR plus DM groups. As compared with DM group, the percentages of spleen CD4+ T cells were declined markedly in both 0.050 and 0.075 Gy plus DM groups (P<0.05, P<0.01), and those of CD8+ T cells increased significantly in LDR plus DM groups (P<0.01), and the ratio of CD4+/CD8+ T cells was declined obviously (P<0.01). Conclusion: The multiple LDR could regulate the immune function in diabetic rats, and rectificate the immunological imbalance in order to protect body. (authors)