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

Abstract 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.