PF248 THE REGULATORY B CELLS IN PATIENTS WITH ACUTE MYELOID LEUKEMIA
Authors: Wang H. , Lv Y. , Zhang G. , Liu Z. 
Published: June 2019

Background:Acute myeloid leukemia (AML) is a hematological malignancy with excessive proliferation of immature myeloid cells, which resulted in impaired differentiation and maturation. The pathogenesis of AML is not yet fully elucidated and it is well recognized that abnormalities in the immune system are involved in the pathogenesis of AML. The regulatory B cells (Breg) are a group of B cells with immunomodulatory function, which mainly exert negative immunomodulatory function by secreting IL‐10 and other cytokines.Due to their immunoregulatory properties, Breg cells may participate in the pathogenesis of AML. The expression profile of Breg cells in AML has so far been poorly explored.Aims:The purpose of our study was to assess the frequency of Breg cells and the relationship between the Breg cells and clinical data in the patients with AML.Methods:A total of 36 in peripheral blood (PB), 10 in bone marrow (BM) AML patients and 15 healthy donors were included for detection of Breg frequency by multicolor flow cytometry. All cases were divided into different groups according to FAB subtypes of leukemia, white blood cell (WBC) levels, ages, cytogenetic characteristics and molecular abnormalities, and were compared the differences of Breg frequency. Survival curve analysis was performed to estimate the value of Breg frequency in prognosis among cases with AML.Results:As Fig.1, the frequency of Bregs were higher in AML patients both in PB and BM compared with that in healthy donors. Nevertheless, no differences between the PB and BM were discovered. A mean value of Breg cells of 25.29 ± 10.68% (range, 4.980–44.70%) was observed in patients compared with 11.16 ± 9.601% (range, 1.050–38.20%) in healthy donors (P < 0.0001). There was no statistical significances in different FAB subtypes of leukemia. The AML patients were splited into two groups by the median of WBC.The AML patients with high‐WBC group had higher frequency of Breg compared with low‐WBC group (P = 0.0251). The frequency of Breg was comparable in the elder and younger group (P = 0.6622). The patients with good prognosis had a decline trend of Breg frequency compared to the medium prognosis group, poor prognosis group and unknown prognosis group, but no differences were found. The patients with Low‐Risk had lower Breg frequency compared to the Medium‐Risk stage (P = 0.0097).The patients were separated into two groups based on the median of WBC, and there were no statistic differences between them(P = 0.3778). When high WBC group was further classified into two groups using the median of Breg exprssion, cases in high‐Breg group showed a short overall survival compared with low‐Breg group (P = 0.0119). Meanwhile, the influence of both ages and Breg cell frequency on patient survival was analyzed. There was similar overall survival between the younger group and the elder group. Following, the patients were divided into four groups based on the median frequency of Breg cells and the median age. The overall survival in edler group with high Breg were significantly shorter than those in younger group with low Breg(P = 0.0272).Summary/Conclusion:For AML patients, the frequency of Breg cells was elevated and high frequency of Breg cells may reveal poor prognosis.image