Fig. 1

Recognition of Cit-containing peptide epitope of fibrin β chain by antibodies in sera of RA patients and healthy blood donors a, b and by isolated B cells c. a Reactivities of RA (n = 170) or healthy (n = 138) serum samples with N-terminally bitotinylated β60-74Cit vs. β60-74Arg bound to neutravidin precoated plates. ELISA ratios were calculated (OD with β60-74Cit /OD with β60-74Arg). Data were analyzed with the Mann–Whitney test, and the median OD ratio of RA samples was 1.68, interquartile range 0.95–6.33, and the median OD ratio of healthy samples was 0.91, interquartile range 0.81–1.07 (***p <0.001). b Receiver operating characteristic curve analysis, area under the curve value for β60-74Cit: 0.7661. c Binding of β60-74Cit and β60-74Arg-coated fluorescent microspheres to prestimulated B cells from β60-74Cit seropositive or seronegative RA patients and from healthy individuals (n = 3/group, ELISA ratios of the selected β60-74Cit seropositive RA patients were between 10 and 15). Bars show means ± SD, *p <0.05. OD optical density, RA rheumatoid arthritis, H healthy