An Analysis Of The CD4~+ T Cell Subsets And Their Clinical Significance In Patients With Primary Immune Thrombocytopenia Based On CD25 And CD127 Phenotype

Objective: Primary immune thrombocytopenia(ITP) is a kind of hemorrhagic disease which is characterized by thrombocytopenia and caused by abnormal autoimmune. Regulatory T cells(Tregs) paly a role of immune suppression, and the decreased amount or weakened function of these cells may be involved in the occurrence of ITP. By detecting the surface marker CD25 and CD127 of CD4~+T cells, we were able to analyze the distribution of Tregs as well as other CD4~+ T cell subsets in the peripheral blood of patients with ITP, aiming to determine whether there were disparities between ITP patients and health controls, and what’s more, whether there was a correlation of these subsets with the response to glucocorticoid treatment.Methods: CD4~+T cells in peripheral blood were detected by flow cytometry in 44 newly diagnosed ITP patients and 53 healthy controls.According to the expression of CD25 and CD127 on the cell membrane, four subsets can be defined including Tregs. Detecting the ratio of each subsets to CD4~+T cells and the proportional relationship between each other respectively,then comparing the differences in the above indexes between ITP patients and healthy controls. Patients were followed up, and their response were supervised at one, two, and three weeks after the initiation of glucocorticoid treatment respectively, and analyzing whether there were differences in the above indexes of different treatment response patients at the above time points, so as to infer whether there was a predictive value of these indexes tothe glucocorticoid treatment response.Results:1. The level of CD4~+CD25+/high CD127+T cells in ITP patients was higher than healthy controls(P=0.03); the ratio of Tregs to CD4~+CD25+/high CD127+T cells in ITP patients was lower than healthy controls(P=0.003); there was no difference in the level of CD4~+CD25-CD127+T cells 、 Tregs 、CD4~+CD25-CD127-T cells and the ratio of Tregs to CD4~+CD25-CD127-T cells between ITP patients and healthy controls before treatment(P>0.05).2. One, two and three weeks after the initiation of glucocorticoid treatment, there were significant differences in the ratio of Tregs to CD4~+CD25+/high CD127+T cells in patients with different curative effects(P1=0.006,P2=0.001,P3=0.01); But the ratio of Tregs to CD4~+CD25-CD127-T cells was different between patients with different curative effect after two weeks of treatment(P=0.021) and there was a statistically significant difference in the level of CD4~+CD25-CD127-T cells between patients with different curative effects after two weeks of treatment(P=0.024).3. According to the ratio of Tregs to CD4~+CD25+/high CD127+ T cells,whether CR or non-CR was achieved can be predicted after three weeks of glucocorticoid therapy(AUC=0.749, P=0.005), and the optimal cut-off value was 0.335; However this ratio was not effective for predicting CR+R or NR(AUC=0.741, P=0.06).4. According to the ratio of Tregs to CD4~+CD25-CD127-T cells,whether CR or non-CR was achieved can be predicted after two weeks of glucocorticoid therapy(AUC=0.726, P=0.01), and the optimal cut-off value was 0.525; However this ratio was not effective for predicting CR+R orNR(AUC=0.712, P=0.708).Conclusions:1. The activation of CD4~+T cells and the relative deficiency of CD4~+CD25+/high CD127low/-Tregs may participate in the pathogenesis of ITP.2. The ratio of Tregs to CD4~+CD25+/high CD127+T cells, and the raito of Tregs to CD4~+CD25-CD127-T cells may have significance in predicting the response to standard-dose glucocorticoid therapy, but need to be further confirmed in studies involving more patients.