Aberrant Frequency of IL-10-Producing B Cells and Its Association with Treg/Th17 in Adult Primary Immune Thrombocytopenia Patients

Background . Regulatory B cells (Breg) are a distinct B cell subset with immunoregulatory properties. Pivotal to Breg function is interleukin-10. This study was to investigate the role of IL-10-producing B cell (B10) and its association with Treg and Th17 subsets in immune thrombocytopenia (ITP) patients. Methods . Peripheral blood mononuclear cells from ITP patients and controls were stimulated with PMA, ionomycin, and Brefeldin A. The frequencies of CD19 + IL-10 + B cells, CD3 + CD4 + IL-17 + Th17 cells, and CD4 + CD25 hi Foxp3 + Treg cells were analyzed by flow cytometry. The mRNA expression of Foxp3 and ROR γ t was detected by real-time quantitative PCR. Results . The number of B10 cells was elevated in ITP patients. After first-line therapies, it remained at high level in patients who achieved complete or partial response but decreased in those who acquired no response. There was a positive correlation between B10 cells and Tregs in ITP both before and after therapies. The ratio of Treg/Th17 decreased in ITP, and it strongly correlated with B10 cells. Conclusions . The frequency of B10 cells is elevated in ITP and it correlates with both the Tregs counts and the Treg/Th17 ratio. B10 cells to regulate functional T cell subsets might be impaired in patients with ITP.