Elevated IL-35 in bone marrow of the patients with acute myeloid leukemia

Acute myeloid leukemia (AML) is the most common hematological malignancy in adults, but the etiology of it remains poorly understood. IL-35 is a recently described cytokine composed of an IL-12 subunit p35 and an IL-27 subunit Epstein–Barr virus induced gene 3 (EBI3), and has an immunosuppressive effect on inflammation through induction of regulatory T cells (Tregs) and suppression of Th1 and Th17. Recently, we have illustrated that concentrations of IL-35 in peripheral blood are up-regulated in newly diagnosed (ND) AML patients. However, whether IL-35 in bone marrow is increased in AML patients is not clear. In this study, we examined IL-35 in bone marrow by various methods including RT-PCR, ELISA, FCM and IHC, and found that IL-35 levels are also increased significantly in bone marrow of adult AML patients. Furthermore, we investigated that concentrations of bone marrow IL-35 in ND group were higher than that in complete remission (CR) group and control group, but there was no significant difference compared to that in relapse group. In conclusion, IL-35 was elevated in bone marrow of adult AML patients and this increase was correlated with the clinical stages of malignancy, suggesting that IL-35 is involved in pathogenesis of AML.