Immunophenotype and increased presence of CD4+CD25+ regulatory T cells in patients with acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL), cancer of the white blood cells, is a heterogeneous disease that mainly occurs due to the malignant cloning of original and naive lymphocytes. The aim of this study was to explore the immunophenotype, the percentage of CD4+CD25+ regulatory T cells (Tregs) and the expression of cytokines interleukin (IL)-2, IL-10 and TGF-β in patients with ALL. The immunophenotype and levels of CD4+CD25+ Tregs were detected using flow cytometry in the peripheral blood of 35 ALL patients, with 18 healthy individuals being selected as controls. The results suggested that 22 patients had B cell ALL (B-ALL) and 13 had T cell ALL (T-ALL) among the 35 ALL patients. In B-ALL patients, the surface antigen CD19 was most commonly expressed; in T-ALL patients, CD7 was most common. Furthermore, the percentage of CD4+CD25+ Treg cells in the peripheral blood of B-ALL and T-ALL patients was higher compared to that of healthy individuals (P<0.05). Additionally, IL-10 and TGF-β levels in cell culture supernatants from B-ALL and T-ALL patients were higher compared to those in the controls (P<0.05); IL-2 levels were lower in ALL patients. No significant differences were observed in the levels of CD4+CD25+ Treg cells, IL-2, IL-10 or TGF-β in B-ALL versus T-ALL patients. The authors concluded that CD19 and CD7 may serve as diagnostic markers of B-ALL and T-ALL, respectively. The increased presence of CD4+CD25+ Treg cells and the altered levels of secreted cytokines are indicative of an immunosuppressive mechanism in the pathogenesis of ALL.