The aim of this study was to determine the frequency of anti-cardiolipin antibodies (aCL) and anti-β2 glycoprotein I antibodies (aβ2GPI) among Tunisian patients with rheumatoid arthritis (RA).
Ninety RA patients with positive anti-cyclic citrullinated antibodies (anti-CCP) and 90 healthy blood donors (HBD) were studied. aCL and aβ2GPI of isotype IgG, IgA and IgM were detected by ELISA.
The frequency of antiphopholipid antibodies (aPL) (aCL and/or aβ2GPI) was significantly higher in patients with RA than in HBD (35.5% vs 11.1%, P = .0001). The frequencies of aCL and aβ2GPI were significantly higher in patients than in healthy subjects (15.5% vs 5.5%, P = .04 and 32.2% vs 11.1%, P = .0005 respectively). aβ2GPI-IgA were significantly more frequent in patients than in the control group (26.7% vs 7.8%, P = .0007). In patients, aβ2GPI-IgA were significantly more frequent than aβ2GPI-IgG (26.7% vs. 6.7%, P = .0003) and aβ2GPI-IgM (26.7% vs 5.6%, P = .0001). In RA patients, the frequency of aβ2GPI was significantly higher than that of aCL (32.2% vs 15.5%, P = .008). aβ2GPI-IgA was significantly more frequent than aCL-IgA (26.7% vs 4.4%, P = .00005). The average titer of anti-CCP in aPL positive patients was significantly higher than in aPL negative patients (170.6 ± 50 RU/mL vs 147.7 ± 51 RU/mL, P = .04). Significant correlation was found between aβ2GPI-IgA and anti-CCP (r = .235, P = .026).
aPL and particularly aβ2GPI-IgA are frequent in RA and are correlated with anti-CCP.