Background Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of autoantibodies to the components of the cell nucleus. Antiphospholipid antibodies of IgA isotype though excluded from antiphospholipid syndrome (APS) classification criteria were yet considered of importance in the development of the disease.
Objectives The aim of the study was to clarify the significance of the different anti-β2GPI isotypes among Egyptian lupus patients with associated APS.
Methods The study included 54 SLE patients (27 with APS and another 27 without). Patients with other known causes of thrombophilia were excluded. The mean age of the patients in those with APS was 27.06±5.825 years while in those without was 29.09±7.46 years. The disease duration was also comparable. The patietns were fully examined and disease activity (SLEDAI) and damage index (SLICC) assessed. The anti-β2GPI isotypes were assessed.
Results In those without APS, the most specific antibodies were in the following order: LA (81.5%), aCL (62.96%) and lastly anti-β2-GPI (48.1%). Regarding sensitivity of aPL among SLE patients with APS, anti-β2GPI antibodies were the most sensitive (59.3%) followed by LA (40.7%) and aCL (22.2%).Among anti-β2-GPI isotypes, the most sensitive isotype was IgA (48.1%) followed by IgG and IgM (14.8% for each). Among aCL isotypes, the most sensitive isotype was IgG (14.8%) followed by IgM (11.1%) and lastly IgA (0%). Anti-β2GPI antibodies and LA seem to contribute to APS pathogenesis more than aCL antibodies. In patients with positive anti-B2GPI IgA, there was a significantly increased dural sinus thrombosis (P=0.025), Autoimmune thrombocytopenia (P=0.03) and leukopenia (P=0.017).
Conclusions Although anti-β2GPI, including its IgA isotype, is less specific than LA and aCL, it seems to contribute to the pathogenesis of thrombotic and non thrombotic manifestations of SLE and APS including DVT, dural sinus thrombosis, pregnancy morbidity, leucopenia and autoimmune thrombocytopenia.
Disclosure of Interest None declared