Regulatory B10 cells are decreased in patients with rheumatoid arthritis and are inversely correlated with disease activity

OBJECTIVE: Regulatory interleukin-10 (IL-10)-producing B cells (B10 cells) have been shown to prevent and cure collagen-induced arthritis in mice. In humans, very little is known about B10 cells in rheumatoid arthritis (RA). Several B cell subsets, such as CD24(high) CD38(high) , CD24(high) CD27+, and CD5+ B cells, were suggested to be precursors of B10 cells. We aimed to analyze these B cell subsets and B10 cells in RA patients and healthy controls. METHODS: B10 cells were generated from peripheral blood mononuclear cells stimulated for 24 hours with CpG and for 4 hours with phorbol 12-myristate 13-acetate/ionomycin/brefeldin A. Intracellular B cell IL-10 was assessed by flow cytometry. Thirty-one controls and 99 RA patients were included. RESULTS: After multiple adjustments, levels of CD24(high) CD38(high) , CD24(high) CD27+, and CD5+ B cells were found to be similar in RA patients and controls. Levels of B10 cells were lower in RA patients than in controls, especially in patients with RA of