Effect on T cell subsets and secretion of IFN-γ and IL-17 after exposure to ⁶⁰Co lethally total body irradiation in mice

Abstract

To investigate the effects of letherally total body irradiation (TBI) on distribution of T-lymphocyte subtypes and their cytokine expression. The BALB/c mice were divided randomly into ⁶⁰Co gamma rays TBI group and control group. Mice were sacrificed 7 days after irradiation. The lymphocytes in spleens, mesenteric lymphonodes, livers and bone marrow were collected and counted. Changes of CD4(+) T and CD8(+) T cell subsets as well as the expressions of IFN-γ and IL-17 were analyzed by flow cytometry. (1)Compared with control group, the total number of lymphocytes in marrow, spleen, lymph node and liver distinctively decreased in TBI group [(5.34±1.14)×10⁵ vs (3.08±1.13)×10⁷, (2.10±0.54)×10⁵ vs (2.71±0.83)×10⁷, (5.89±1.07)×10⁵ vs (7.92±1.15)×10⁷ and (3.45±1.01)×10⁵ vs (7.44±0.79)×10⁶, respectively, and the significant differences were observed between two groups in each organ (P<0.05)]. (2)The level of IFN-γ produced by CD4(+) T in spleen, lymph node and liver elevated in TBI group compared to control group, which were (20.77±2.03)% vs (3.69±3.13)%, (6.28±0.46)% vs (1.11±0.17)%, (27.24±5.79)% vs (9.01±1.24)% respectively, the differences between two groups in each organ were significant (P<0.05). (3)Percentages of IFN-γ(+)CD8(+) T in spleen, lymph node and liver in TBI group increased compared to control group [(52.40±9.26)% vs (43.06±1.04)%, (33.56±5.02)% vs (21.83±4.22)%, and (44.27±8.97)% vs (19.32±3.11)%, respectively, and the differences between two groups in each tissue were significant (P<0.05)]. (4)However, IL-17A expressions in CD4(+) T and CD8(+) T cells from spleen and liver were lower than those in control group. TBI induced the reduction of lymphocytes and the expansion of IFN-γ producing Th1 and Tc1 effector cells in mice.