APOH and systemic lupus erythematosus: reported that IgA antibodies against domain 4/5 associated with SLE without thrombosis whereas IgA anti-β2GPI-D1 was not associated with thrombosis or SLE.51 These data are corroborated by a recent report showing that IgA anti-β2GPI from patients with thrombotic APS do not mainly bind domain 1, but instead target three sites in domains 3, 4 and 5.52 Monoclonal antibodies against these epitopes have previously been shown to produce APS in animal models.53 Murthy et al.