RT Journal Article SR Electronic T1 Anti-β2-glycoprotein I IgG antibodies from 1-year-old healthy children born to mothers with systemic autoimmune diseases preferentially target domain 4/5: might it be the reason for their ‘innocent’ profile? JF Annals of the Rheumatic Diseases JO Ann Rheum Dis FD BMJ Publishing Group Ltd and European League Against Rheumatism SP 380 OP 383 DO 10.1136/ard.2010.137281 VO 70 IS 2 A1 Laura Andreoli A1 Cecilia Nalli A1 Mario Motta A1 Gary L Norman A1 Zakera Shums A1 Susan Encabo A1 Walter L Binder A1 Monica Nuzzo A1 Micol Frassi A1 Andrea Lojacono A1 Tadej Avcin A1 Pier-Luigi Meroni A1 Angela Tincani YR 2011 UL http://ard.bmj.com/content/70/2/380.abstract AB Background Anti-β2-glycoprotein-I (anti-β2GPI) were demonstrated to be pathogenic in the antiphospholipid syndrome (APS). However, they can be detected in patients with no features of APS, especially those affected by systemic autoimmune diseases (SAD), and so in healthy children. It has been suggested that anti-β2GPI against domain 1 (D1) associate with thrombosis, while those recognising domain 4/5 (D4/5) are present in non-thrombotic conditions. Objective To evaluate the fine specificity of anti-β2GPI in adults and infants. Methods Three groups were examined—group A: 57 1-year-old healthy children born to mothers with SAD; group B: 33 children with atopic dermatitis; group C: 64 patients with APS. Subjects were selected based on positive anti-β2GPI IgG results. Serum samples were tested for anti-β2GPI IgG D1 and D4/5 using research ELISAs containing recombinant β2GPI domain antigens. Results Children (A and B) displayed preferential IgG reactivity for D4/5, whereas patients with APS were mainly positive for D1. No thrombotic events were recorded in groups A and B. Conclusions The specificity for D4/5 suggests that anti-β2GPI IgG production in children born to mothers with SAD is a process neither linked to systemic autoimmunity nor related to the maternal autoantibody status. This unusual fine specificity might, at least partially, account for the ‘innocent’ profile of such antibodies.