Background There is an increasing interest in the study of domain reactivity of antibodies against β2 glycoprotein I (anti-B2GPI) in patients with antiphospholipid syndrome (APS). Antibodies targeting domain 1 of the molecule (anti-D1) as the most relevant autoantibody subpopulation. Previous information of anti-D1 B2GPI comes from APS cohorts with Caucasian, Asian, and African-American patients. However, there are no studies in Mestizo and Afro-Latin American patients.
Objectives Our aim was to evaluate the prevalence of Anti-D1 B2GPI antibodies in a cohort of Colombian patients with systemic lupus erythematosus (SLE) with and without thrombosis, primary APS and patients with previous history of recurrent miscarriages (RM) without APS criteria.
Methods In this cross-sectional study we measured Anti-D1 B2GPI antibodies in a group of patients from Rheumatology Department, Coagulation clinic and Recurrent Pregnancy Loss Program at the Reproduction Group at Hospital San Vicente Fundaciόn and Universidad de Antioquia, respectively, at Medellín, Colombia. Anti-D1 B2GP1 antibodies were tested using a chemiluminescent immunoassay (QUANTA Flash B2GPI IgG, Inova Diagnostics). Mann-Whitney tests were used to compare data.
Results One hundred and seventy seven (median age 33.5±12.1 years; 89% women) patients were included. One hundred thirty eight patients had SLE (78%), 27 primary APS (15%) and 13 RM (7%). Fifty five (31%) out of 177 patients had history of thrombosis and 41 (23%) of pregnancy losses. Overall, Anti-D1 B2GPI antibodies were positive (>20 CU) in 35 (20%) of patients. Anti-D1 B2GPI were positive in 23%, 17% and 0% of patients with primary APS, SLE and RM, respectively. Overall, serum Anti-D1 B2GPI were significantly higher in patients with than without previous thrombosis (149.1±336.1 vs 16.3±61.8 CU, p<0.0001) and in patients (SLE or primary APS) with previous history of pregnancy losses (40.2±123.1 vs 21.0±74.5 CU, p=0.04). Anti-D1 B2GPI were significantly higher in patients with primary APS vs SLE with thrombosis, and in patients with SLE with thrombosis vs SLE without thrombosis (Figure). No clinical associations were found among Anti-D1 B2GPI antibodies and other APS features.
Conclusions Serum titers of Anti-D1 B2GPI antibodies were more than 9 times and 2 times higher in patients with thrombosis and pregnancy losses, respectively. In addition, serum titers were significantly higher in patients with primary APS than in SLE patients with thrombosis. Whether Anti D1- B2GPI antibodies titers are useful to differentiate patient with primary and secondary APS requires further analysis.
Acknowledgements JA Gόmez-Puerta was supported by Colciencias (conv. 656 de 2014). Anti-D1 B2GPI antibodies were provided by Inova, Werfen, Colombia
Disclosure of Interest None declared
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