Fig. 5

Scatter plots of selected biomarker candidates in healthy controls and RF- and anti-CCP-positive/negative RA. Proteins altered among rheumatoid (RF)- and anti-CCP (ACCP)-positive or -negative RA patients relative to those in the healthy controls were selected. a–d Angiotensinogen, retinol-binding protein-4 (RBP4), serum amyloid A-4 protein (SAA4), and vitamin D-binding protein (VDBP) profiles were compared between healthy controls and RA patients in accordance with the antibody titer. The number of healthy controls and RA patients was 251 and 230 (RF+/ACPA+ n = 121, RF+/ACPA− n = 47, RF−/ACPA+ n = 33, RF−/ACPA− n = 29), respectively. Plots indicate individual protein abundance in each group. Data are presented as mean ± SD values. Independent samples t tests were used to determine the statistical significance **p < 0.001. HC, healthy controls; RA, patients with rheumatoid arthritis