[Research of regulative factors on CD8(+)HLA-DR(+) effector T cells in severe aplastic anemia]

To explore the regulative factors on CD8(+)HLA-DR(+) T cells in the patients with severe aplastic anemia (SAA) and examine the roles of these cells in the immunopathogenesis of SAA.CD8(+)HLA-DR(+) T cells were sorted from bone marrow mononuclear cells of 13 SAA patients from July 2011 to March 2012 by magnetic activated cell sorting system and were divided into 3 groups: interleukin 2 (IL-2) group (0, 0.1, 1, 10, 100 and 1000 U/ml), cyclosporine A (CsA) group (addition of 400 ng/ml CsA in each IL-2-containing well),receptor antagonist group (addition of IL-2 receptor antagonist 8 µg/ml in each IL-2-containing well). Then cell proliferation rate was evaluated by MTT assay after a 72-hour culturing. Bone marrow mononuclear cells of the SAA patients were divided into CsA group, IL-2 group and control group and cultured for 18 hours and another 4 hours following the dosing of phorbol ester. The expression of tumor necrosis factor β (TNF-β) in CD8(+)HLA-DR(+) T cells was analyzed by flow cytometry.The cell proliferations of IL-2 wells at the concentrations of 10, 100 and 1000 U/L (0.36 ± 0.12, 0.41 ± 0.12, 0.46 ± 0.14) were significantly higher than those of the control wells (0.23 ± 0.11), CsA group (0.18 ± 0.05, 0.19 ± 0.00, 0.20 ± 0.04) and receptor antagonist group (0.18 ± 0.05, 0.17 ± 0.04, 0.18 ± 0.03, all P0.05). No statistic difference existed between CsA and receptor antagonist groups (P0.05). The expressions of TNF-β of CD8(+)HLA-DR(+)T cells of the IL-2 group were higher than those of the control group (64% ± 25% vs 46% ± 22%) whereas the CsA group (27% ± 20%) were lower than those of the control group (both P0.05).IL-2 can significantly stimulate the proliferation of CD8(+)HLA-DR(+) T cells and accelerate the in vitro secretion of TNF-β in SAA patients. The proliferation may be inhibited by CsA and receptor antagonist. And the expression of TNF-β is suppressed significantly by CsA.