Background The regulatory function of B cells is beginning to be understood, and several subsets of regulatory B cells have been suggested. A recent study suggested that the human B cell secreting IL-10 may have a central role in the regulatory function in immune system. However, the roles of regulatory B cells secreting IL-10 (B10 cells) was not established in rheumatoid arthritis (RA) pathogenesis.
Objectives To know the exact status of IL-10+ B cells, we investigated the induction of B10 cells in the RA patients and analyzed disease activity.
Methods CD19+ cells in peripheral blood mononuclear cells were purified from blood samples of RA patients and age and sex matched healthy controls, and stimulated with CD40 ligand and CpG for 48 hours. Intracellular IL-10 was analyzed using flow cytometry.
Results The proportion of IL-10+ B cells to total B cells in RA patients was significantly higher than those in controls (RA, 4.44% ± 3.44% vs. healthy control 2.44% ± 1.64%, p = 0.033). However, the proportion of IL-10+ B cells to total B cells was correlated negatively with disease activity (r = –0.398, p = 0.040). Although age was correlated with IL-10+ B cells positively (r = –0.525, p = 0.004), age was also correlated with disease activity (r = 0.409, p = 0.031) in RA patients in this study. In healthy controls, age was not correlated with IL-10+ B cells (r = 0.035, p = 0.895). Thus, the association could be attributed to disease activity. To evaluate the effect of soluble factors in serum, IL-10+ B cell was induced with adding patients’ serum. The proportion of IL-10+ B cells was increased with serum. However, there were no differences between active RA and inactive RA group.
Conclusions The proportion of induced IL-10+ B cell increased in RA patients compared to healthy control and was negatively correlated with disease activity in rheumatoid arthritis. Adding active and inactive RA patients’ sera, the proportion of IL-10+ B cell did not different between two groups.
Disclosure of Interest None Declared
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