Cyclosporine A Effect the CD28 Expression on CD8+T Cells of Patients with Aplastic Anemia through down Regulate FLIP.

Objective The exact reason of aplastic anemia is still unknown. Recently more and more researchers realized that immune factors play an important role in aplastic anemia. In this study, we detected the expression of CD28 on different subgroups of T cells in patients with aplastic anemia and furthermore studied the effect of cyclosporine A to CD28 and FLIP on these cells. Method 21 patients and 15 healthy controls were investigated. The Expression of CD4CD28 and CD8CD28 on patients’ T cells was detected with FCM; patients’ CD8⁺T cells were purified with Mini MACR system, then the expression of FLIP, caspase-8 in CD8⁺T cells were analyzed by RT-PCR; we also detected the expression of CD28, FLIP and caspase-8 in patients’ CD8⁺T cells after incubation with cyclosporine A.

Result: The percentage of CD8⁺CD28⁻T cells in the patients is significantly higher than that of normal controls (30.45±5.26% versus 19.32±4.72%, p<0.05) and it can be induced to return to normal after effective treatment with Cyclosporine A; the expression of FLIP in patients’ purified CD8⁺ T cells is higher than that in healthy controls’ CD8⁺ T cells, but there is no difference in the expression of caspase-8; after being cultured with Cyclosporine A, the expression of FLIP in patient’s CD8⁺T cells was down regulated and the quantity of CD28 on the surface of patient’s CD8⁺T cells increased significantly (28.3±5.1% versus 40.6±7.71%40.6±7.71%).

Conclusion: The increased expression of FLIP in patients’ CD8⁺T cells is related to the increased percentage of CD8⁺CD28⁻T cells in patients’ peripheral blood. Cyclosporine A can down regulate the FLIP expression and correct the abnormal percentage of CD8⁺CD28⁻T cells in patients with aplastic anemia.