Study On The Imbalance Of Peripheral Blood Treg/Thl7Cells In Childhood Aplastic Anemia

Objective：To investigate the levels of CD4+CD25+regulatory T cells(Treg),Th17cells and their related cytokines in the peripheral blood ofchildhood aplastic anemia(AA),and explore the roles of Treg/Th17cellimbalance in pathogenesis of AA in children and the clinical significance.Methods: There were35cases of children with AA,19patients with severeaplastic anemia(SAA),16patients with non-severe aplastic anemia(NSAA).The AA patients were further divided into effective therapy group(n=13)and ineffective treatment group(n=15).25healthy subjects were selectedas normal control group. The flow cytometry was used to evaluate theproportion of peripheral blood Treg cells and Th17cells in childhoodaplastic anemia and healthy children. The levels of plasma IL-17and IL-6were assayed by enzyme-linked immunosorbent assay(ELISA).T-test andChi-square test were used for inter-group comparison and Pearon’s linearanalysis was used for correlation analysis.Results: Compared with healthy controls, the percentages of Th17cells andthe concentration of IL-17and IL-6in the peripheral blood of childhoodaplastic anemia increased significantly [(1.45±0.28)%vs (0.45±0.10)%；（185.96±40.42）pg/ml vs（120.47±18.39）pg/ml、（20.78±5.49）pg/ml vs（10.44±2.51）pg/ml](P<0.01), while the ratio of Treg cells and Treg/Th17was markedly lower[（4.05±1.07）%vs (6.96±0.79)%；（2.89±0.88）VS（15.77±2.77）](P<0.01). The ratio of Treg cells and Treg/Th17in patients with SAA was lower than that in patients with NSAA[respectively for（3.37±0.79）%，(2.47±0.78) and （4.84±0.78）%,(3.39±0.75),P<0.01], but thelevel of Th17cells,IL-17and IL-6didn’t markedly changed [respectivelyfor (1.43±0.31)%，(191.76±50.62) pg/ml,(21.65±6.26) pg/ml and （1.46±0.23）%,(179.08±23.13) pg/ml,(19.75±4.37) pg/ml, P>0.05].Comparedwith ineffective treatment group, the proportion of Th17cells in effectivetherapy group decreased markedly,while the ratio of Treg cells andTreg/Th17increased significantly [(0.56±0.15)%vs (1.44±0.26)%；（6.63±1.01）%vs (4.26±1.04)%；（12.92±4.72）VS（3.09±1.00）](P<0.01). Therewere no significant difference in the proportion of Treg or Th17cells orthe ratio of Treg/Th17between effective therapy group and normal controlgroup (P>0.05). The proportion of Th17cells in the peripheral blood ofchildhood aplastic anemia were positively correlated to the plasma levelsof IL-17and IL-6(r=0.67,P<0.01；r=0.57,P<0.01),but the percentage of Treghad negative correlation with the plasma concentration ofIL-6(r=-0.39,P<0.05).Conclusion: The imbalance between Treg cells and Th17cells resulted fromdecreased ratio of Treg cells and increased ratio of Th17cells may playa critical role in immunological pathogenesis of childhood aplastic anemia.High expression of IL-17may be one of the mechanism of Th17cells inpathogenesis of childhood aplastic anemia,while the increase expressionof IL-6may be one of the factors causing the imbalance of Treg/Th17cells.Furthermore， the imbalance between Treg cells and Th17cells couldcontribute to predicting the disease severity and clinical evaluation ofAA.