Aberrant expression of T cell activation markers and upregulation of Tregs in bone marrow and peripheral blood in acute myeloid leukemia patients

Background: T cells' function and activation and the immunosuppressive effect of regulatory T cells (Tregs) play a pivotal role in the occurrence and progression of acute myeloid leukemia (AML). In this study, we investigate the expression of T cell activation markers and quantity of Tregs in bone marrow (BM) and peripheral blood (PB) from AML patients and further characterized their correlation with BM leukemic blasts. Methods: Expression of CD25, CD38, CD69, and HLA-DR on the surfaces of CD4(+) and CD8(+) T cells and the quantity of Tregs in BM and PB from new diagnosed (ND), relapsed-refractory (RR), complete remission (CR) AML patients were measured via flow cytometry. Results: Compared to normal controls (NC), we found higher proportion of CD4(+) CD69(+) T cells, CD8(+) CD69(+) T cells and Tregs in PB. CD8(+) CD38(+) T cells and CD8(+) HLA-DR+ T cells in RR were significantly higher than ND, CR and NC). Tregs were normalized when AML patients achieved CR. Moreover, there was a minor positive correlation between AML blasts and CD8(+) CD25(+) T cells or Tregs, while AML blasts had a minor negative correlation with CD4(+) CD69(+) T cells. Conclusion: Abnormal activation markers of T cells and Tregs may be involved in the pathological mechanism of ND and RR AML. Our results indicated that CD8(+) CD38(+) T cells and CD8(+) HLA-DR+ T cells might be RR markers of AML patients. Furthermore, Tregs could be used as clinical indicators to evaluate prognosis for AML patients.