Regulatory B10 cells have the potential to differentiate into Ab-secreting plasma cells (84.16)

Abstract

Abstract B cells with IL10-dependent regulatory functions have been observed in mouse models of autoimmunity, colitis and in T-dependent immune responses such as delayed-type hypersensitivity. The rare regulatory B10 cell subset that is competent to produce IL10 was examined in the current studies using two distinct lines of reporter mice to track IL10 production. Tiger mice expressed both IL10 and GFP proteins from the same transcript, with GFP expression faithfully marking IL10 production by B10 cells. By contrast, 10BiT mice express Thy1.1 as a separate transcript. While Thy1.1 and IL10 transcripts appeared concurrently as determined by real-time RT-PCR, cell surface Thy1.1 expression was delayed by >24 h and persisted on the cell surface even after a decline in IL10 production. Thus, Thy1.1 expression functioned as a marker for B10 cells after IL10 induction in vivo during later stages of differentiation. Following LPS stimulation in vivo, Thy1.1+ B10 cells upregulated CD138 expression and secreted IgM. Likewise, B10 cells from wild type mice were a major source of secreted Ab following LPS-stimulation ex vivo. Thereby, B10 cells are competent to express IL10 following LPS stimulation in vivo, which is followed by their differentiation into IgM-secreting plasma cells.