The effects of γ-ray radiation on hematopoiesis and T lymphocyte subset function

Abstract

Objective To observe the effects of whole body γ-ray radiation on hematopoiesis and cytokines related to T cell subsets in mouse,to detect the expression of transcription factors of splenic T cell subsets,and to investigate the correlation between hematopoiesis injury and abnormal immune function.Methods Totally 50 BALB/c mice were divided into radiation group and blank control group with the random number table method.The former group were given 5.5 Gy 60Co γ-ray radiation on whole body and another received sham radiation.The numbers of white blood cells and platelets of radiation group were counted at 4,8,12 and 20 d after radiation,and these numbers of blank control mice were counted only at 20 d.Hematopoietic tissue proliferation was evaluated by biopsy sections of mice femur.The contents of Th1,Th2,and Th17 in peripheral blood were detected with cytometric bead array (CBA).The expressions of T-bet/GATA-3 and RORγt/Foxp3 proteins related to the differentiation of T cell subsets in spleen tissue were measured by Western blot.Results The numbers of white blood cells and platelets of radiation group mice were reduced obviously (t WBC =18.48,15.72,9.79,3.30; t PLT =22.52,19.74,11.78,4.70,P ＜ 0.05) compared with blank control group.Biopsy sections showed that bone marrow hematopoietic cells of the radiated mice were less than those of blank group,and adipocytes became more.At 8 d,the marrow suppressions were more obvious than those at 20 d.Serum contents of Th1 cytokines IFN-γ,TNF-α and Th2 cytokines IL-4,IL-6 in the radiation group were higher than those in the blank control group at 8 and 12 d(t IFN-γ =2.93,3.36,t TNF-α =6.09,8.11,6.43,4.49,tIL-4 =4.49,3.18,t IL-6=5.11,8.67,6.67,8.55,P＜0.05).IL-17A secreted mainly by Th17 cells was also higher than the blank (t =3.68,6.24,5.32,4.06,P ＜ 0.05).Compared with the blank control group,the expression of T-bet protein increased significantly (t =5.64,2.75,3.56,4.65,P ＜ 0.05),and the expressions of GATA-3,RORγt,and Foxp3 proteins decreased at 4,8 and 12 d except the RORγt at 20 d (tRORγt =6.79,4.31,4.47,tGATA-3 =3.88,8.06,2.84,3.23,tFoxp3 =10.00,8.06,2.89,5.93,P＜ 0.05).Conclusions 5.5 Gy whole body γ-ray radiation inhibits bone marrow hematopoiesis of BALB/c mice and makes the differentiation and function of T cells to be abnormal,which may be associated with bone marrow hematopoiesis obstacle. Key words: γ-ray radiation; T cell subsets; Cytokines; Transcription factors