Abnormal quantity of regulatory T cells in peripheral blood of patients with severe aplastic anemia and its clinical significance

This study was purposed to investigate the role of regulatory T cells(Treg) in the immune unbalance for patients with acquired severe aplastic anemia( SAA). The flow cytometry was used to detect the quantity of CD4+CD25+CD127dimTregs,T cell subset( CD4+/CD8+ratio),dendritic cell( DC) subset( mDC /pDC ratio) in 44 SAA patients(25 untreated patients and 19 recovery patients) and 23 normal controls. The correlation between Tregs and T cell subset,DC subset and hemogram were analyzed. The results showed that the percentage of CD4+CD25+CD127dim Tregs in peripheral blood lymphocyte( PBL) of untreated patients was(0. 83 ± 0. 44)%,which was obviously lower than that in recovery patients(2. 91 ± 1. 24)% and normal controls(2. 18 ± 0. 55)%( P 0. 05),but the difference was not statistically significant between latter two groups. The ratio of CD4+/CD8+was(0. 5 ± 0. 3) in untreated patients,which was obviously lower than that in recovery patients(1. 2 ± 0. 4) and normal controls(1. 11 ± 0. 24)( P 0. 05). The ratio of mDC /pDC was(3. 08 ± 0. 72) in untreated patients,which was significantly higher than that in recovery patients(1. 61 ± 0. 49) and normal controls(1. 39 ± 0. 36)( P 0. 05). The percentage of CD4+CD25+CD127dimTregs in PBL positively correlated with CD4+/CD8+ratio( r = 0. 695,P 0. 01),and that negatively correlated with mDC /pDC ratio(r =- 0. 796,P 0. 01). There were significant positive correlations between CD4+CD25+CD127dimTregs /PBL and WBC,Ret%( r = 0. 761,0. 749 respectively,P 0. 01). It is concluded that the decrease of CD4+CD25+CD127dimTregs quantity in SAA may be one of mechanisms underlying bone marrow failure resulting from the deterioration of immune tolerance and hyperfunction of T-cells.