Bone marrow IRF4 level in multiple myeloma: an indicator of peripheral blood Th17 and disease

// Hua Bai 1, * , Shuang Wu 1, * , Rong Wang 1 , Ji Xu 1 and Lijuan Chen 1 1 Department of Hematology, First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China * These authors have contributed equally to this work Correspondence to: Lijuan Chen, email: chenljb@126.com Keywords: multiple myeloma, T-help cells, interferon regulator factor 4, interleukin-17 Received: March 29, 2017 Accepted: July 12, 2017 Published: August 03, 2017 ABSTRACT Interferon regulator factor 4 (IRF4) is characterized to be a member of interferon regulatory family, which is predominantly expressed in bone marrow plasma cells of patients with multiple myeloma (MM). Recent studies indicated IRF4 is critical for T-help cells (Th17) differentiation and interleukin-17 (IL-17) secretion. Here, a total of 58 MM patients were enrolled in this study, the proportions of Th17 cells and T regulatory (Treg) cells in peripheral blood mononuclear cells (PBMCs) were determined by flow cytometric analysis. Immunohistochemistry was employed to detect the IRF4 expression in bone marrow. Herein, we observed a significant increase of IRF4 in bone marrow accompanied with a notable up-regulation of Th17 cells in PBMC within MM patients compared with healthy donors. Furthermore, the proportions of Th17 cells and serum IL-17 levels were higher in patients with stage III than stage I & II MM patients, and those parameters were positively correlated with the expression of IRF4 in these cases. These results for the first time indicate that a crosstalk between IRF4 and Th17 cells is associated with MM prognosis, and IRF4 may be served an important target for MM immunotherapy.