To study the prevalence of antibody to citrullinated human fibrinogen (ACF) in rheumatic diseases and the diagnostic values in rheumatoid arthritis.
Human fibrinogen was deiminated by the peptidylarginine deiminase (PAD) in the presence of Ca2+ in vitro. ACF was detected by ELISA in 352 patients with rheumatic diseases (183 RA, 121 SLE and 48 OA) and 108 healthy controls. The sensitivity and specificity in RA were calculated and the correlations between ACF and the clinical and laboratory parameters were analysed by SPSS statistical software.
Compared with SLE (25.62%), OA (18.75%) and healthy control (2.78%) respectively, the patients with RA had a significantly higher level of ACF (67.21%, P<0.001). ACF had a sensitivity of 67.21% and a specificity of 84.84% for RA. In the investigated clinical and laboratory parameters of RA, the significant correlations were found between ACF and ESR (r=0.386, P<0.001), anti-CCP antibody (r=0.288, P<0.05) and AKA (r=0.288, P<0.05), respectively. Abnormalities in ESR, radiographic progression, IgM-RF, anti-CCP, AKA and APF were more often in ACF positive patients than in ACF negative patients. Moreover, ACF was positive in 38.00% of IgM-RF negative, 59.81% of AKA negative and 68.22% of APF negative patients, respectively.
ACF is a sensitive and specific antibody in diagnosing RA. The ACF test is also very useful in diagnosing RA with other autoantibodies negative.