ABCs produce anti-chromatin antibodies on stimulation in vitro. ABCs and FO, MZ, and B1 B cells were isolated from C57BL/6 (A-C) or NZB/WF1 (D) mice and cultured for 7 days in the presence of medium or TLR7 agonist. Total IgM (A), IgG (B), and anti-chromatin IgG (C-D) were subsequently measured in supernatant by enzyme-linked immunosorbent assay. (A-B) Bars represent mean (± SEM) of 3 independent experiments. (C-D) Data are representative of 3 independent experiments.