Molecular Machanism Of Regulatory T Cells Dysfunction In Aplastic Anemia

Objective:To investigate the causes and molecular basis of damaged immune function of regulatory T cells with aplastic anemia patients by detecting the number and expression of surface membrane molecules,the nuclear transcription factor FOXP3 of regulatory T cells(Treg) of peripheral blood of patients with aplastic anemia,and differentiation tendency of Treg cells in patients with AA.Methods:45 cases newly diagnosed with AA as a experimental group from May 2014 to February 2015 in Blood Diseases Hospital, Chinese Academy of Medical Sciences(Institute of Hematology) were enrolled in this study.The ratio of male and female is5 to 4,with media age 31(6-77)years old,including non-severe aplastic anemia(non-SAA) 4 cases, severe aplastic anemia(SAA)25 cases,very-severe aplastic anemia(VSAA) 16 cases. Flow cytometry(FCM) was used to detect the number and expression of surface membrane molecules and the nuclear transcription factor FOXP3 of regulatory T cells(Treg) of peripheral blood of patients with aplastic anemia.And further application of PMA / Ionomycin assay is to evaluate the differentiation tendency of Treg cells in patients with AA.All data were processed with SPSS for windows software version 17.0. The means of different samples were compared by using one-way ANOVA. The level of significance was set at 0.05.Graphpad Prime 5 was used to make the figures.Results:1. Treg cell number and expression of nuclear transcription factor FOXP3 of AA patients decreased,and the former is associated with the severity of AA.2. The expression rate of Treg cells membrane surface marker CD39,CD73,PD-1increases.3. Expression of FOXP3+Treg membrane surface antigen in AA patients isabnormality.1) In terms of the FOXP3+Treg,expression of the membrane surface marker CD39,CD73,PD-1 increase; And with the FOXP3-Treg group, these markers are also up-regulated,but without dramatic significance.2) In AA patients, percentages of CD28+FOXP3+Treg 、 TIGIT+FOXP3+Treg are lower;CD28+FOXP3+Treg、TIGIT+FOXP3+Treg positive levels are high though no dramatic differance; also CTLA-4+FOXP3+Treg declined but no statistic significance.4. Expression of FOXP3+Treg antigen in AA subgroup is different.1) Compared with healthy controls, in addition to the non-SAA,CD28+FOXP3+Treg in Patients of SAA,VSAA are lower, with CD39+FOXP3+Treg higher. Not any differance were observed among AA subgroups.2) Compared with healthy controls,CD73+FOXP3+Treg in VSAA patients are much higher.Not any differance were observed among AA subgroups.3)Not any statistic differances were observed among healthy controls,non-SAA,SAA and VSAA.But the decline trend of TIGIT+FOXP3+Treg and CTLA-4+FOXP3+Treg in AA patients still can be found.5. With PMA / Ionomycin ways stimulating, the IFN-r secretion of Treg cells in AA patients increased,IL-4 declined.No statistically significance was found in IL-17 A factor.Conclusion:1.The lower number of Treg in AA patients is associated with the severity of AA.Much less expression of FOXP3 of Treg indicates that immunosupression functin of Treg cells in AA patients defects.2.The decline of regulatory T cell surface receptors expression is one of the mechanisms of malfunction of Treg in patients with AA.3.Treg cells in AA patients have the ability to shift to Th1 cells to make the immune AA patients with adjustment disorder, contributing to the occurrence of aplastic anemia in patients with the disease.