Anti-BB'-Sm antibodies, anticardiolipin antibodies, and thrombosis in systemic lupus erythematosus.

OBJECTIVE

Anticardiolipin antibodies (aCL) are associated with thrombosis in patients with systemic lupus erythematosus (SLE). Our aim was to determine whether there is an association between aCL, anti-Sm antibodies, and thrombosis in patients with SLE.

METHODS

Sera from 153 patients with SLE were studied by ELISA, immunoblotting, and counter-immunoelectrophoresis (CIE) for anti-Sm antibodies, aCL and anti-dsDNA antibodies were detected by ELISA and radioimmunoassay, respectively.

RESULTS

Anti-Sm antibodies were detected in 62 patients (40.5%) by ELISA and in 16 (10.4%) by CIE; IgG-anti-BB'-Sm in 44 (28.7%) by immunoblotting; IgG-aCL in 82 (53.5%), IgM-aCL in 44 (28.7%), and anti-dsDNA antibodies in 128 (83.6%). Anti-Sm and anti-dsDNA antibodies were significantly more frequent in patients with than in patients without aCL. Of the 89 patients with aCL, 36 (40.4%) showed IgG-anti-BB'-Sm antibodies (OR: 4.7; 95% CI: 2-10.5). Thrombosis was present in 20 (22.4%) SLE patients with aCL and in two (3.1 %) SLE patients without aCL (OR: 8.9; 95% CI: 2.4-31.8). Of the 22 patients with thrombosis, five (22.7%) had precipitating anti-Sm antibodies (OR: 3.2; 95% CI: 1.04-9.8) and 14 (63.6%) showed IgG-anti-BB'-Sm antibodies (OR: 5.8; 95% CI: 2.3-14). Anti-BB'-Sm and aCL were significantly more frequent in patients with anti-dsDNA antibodies (32 and 62%) than in patients without these antibodies (12 and 36%) (OR: 3.4 and 2.9; 95% CI: 1.03-11.1 and 1.2-6.7, respectively).

CONCLUSION

IgG-anti-BB'-Sm antibodies are associated with aCL, anti-dsDNA, and thrombosis in patients with SLE. Our findings suggest a possible association between anti-Sm, anti-dsDNA, and aCL responses in these patients.