FBL and rheumatoid arthritis: Therefore, following RA induction, we purified three types of serum IgG fractions for LC-ESI-MS analysis: anti-Fib antibody from cFib-immunized mice (Fib/cFib), total IgG deprived of anti-Fib antibody in the same mice (FT/cFib) and total IgG from naïve mice (total/naive) (Supplementary Figs 8 and 9).