[Effects of Iron Overload on the Apoptosis and Function of Splenic CD8+ T Cells in Mice].

Objective: To investigate the effects of iron overload on apoptosis and function of splenic CD8+ T cells in mice.

Methods: Forty C57BL/6 mice were randomly divided into control groups, Iron overload (IO), IO+NAC and IO+DFX groups. The iron overload model was established by intraperitoneal injection of iron dextran, and saline was injected as the control. The levels of intracellular reactive oxygen species (ROS) and labile iron pool (LIP) were analyzed by measuring the mean fluorescence intensity (MFI) of 2-7 dichlorofluorescein (DCF) or calcein. The ratio of CD8+ T cells and the levels of IFN-γ, TNF-α, Granzyme-B, and perforin in CD8+ T cells were detected by flow cytometry. The CD8+ T cell apoptosis was determined by flow cytometry with Annexin V/PI double staining. Real-time PCR was used to detect the expression of IFN-γ, TNF-α, Granzyme-B, perforin, BCL-2, and bax at mRNA level in CD8+ T cells.

Results: Iron overload was found by spleen iron staining and flow cytometry. The level of intracellular ROS in iron overload (IO) groups was higher than that of the control groups (P<0.01). The percentage of CD8+ T cells in spleen from mice with IO was lower than that in control groups (P<0.05). The expression of IFN-γ and Granzyme-B in CD8+ T cells in IO group were lower than that in control group, the expression of IFN-γ and Granzyme-B at mRNA level in CD8+ T cells was lower than that of control group (P<0.05). CD8+ T cell apoptosis in iron overload group was significantly higher than that in control groups (P<0.01); the expression of BCL-2 at mRNA level was lower than that in control group, but the expression of BAX at mRNA level was higher than that in control group (P<0.05). These effects could be reversed after treating iron-overloaded mice with DFX or NAC.

Conclusion: Iron overload can inhibit the ratio of CD8+ T cells of splenic cells in mice, decrease the expression of IFN-γ, Granzyme-B, increase the apoptosis of CD3+ CD8+/CD8-. These effects may be regulated through increasing the intracellular ROS level, and can be partially reversed after treating iron-overloaded mice with DFX or NAC.