Fig. 5

Effect of anti-CCP and RF positivity on the production of superoxide anions by phagocytes from RA patients. Data are expressed as medians, quartiles and extreme values, and outlier values are indicated. Individuals with RA produced a significantly higher amount of superoxide anion than controls (p = 0.0026, Mann–Whitney test). Positivity for anti-CCP or RF was not statistically associated with increased superoxide anion production (p > 0.05). a: rheumatoid arthritis patients versus healthy control; b: anti-CCP negative versus positive RA patients; c: RF negative versus positive RA patients. The statistical differences are marked in the graphics and in text