Catastrophic antiphospholipid syndrome (cAPS) is a life threatening condition with simultaneous thrombosis in multiple organs that can occur in patients with antiphospholipid antibodies (APL). Predictive biological parameters for cAPS have not been defined yet. Anti-phosphatidylserine/prothrombin antibodies (aPS/PT) of either IgG or IgM isotypes or both have been recently associated with the presence of LA. It has not been determined whether aPS/PT isotypes are correlated to clinical features of antiphospholipid syndrome (APS).
157 sera from patients with cAPS (n=29), 58 sera from patients with APS (n=29) and 31 sera from patients with stable antiphospholipid antibodies (APS, either aCL, ab2GPI or LA; ACL levels between 25 and 75 UGPL) without clinical APS manifestations (noAPS; n=19), primarily collected for aCL, b2gPI and/or LA detection, were tested on individual isotype aPS/PT IgG and aPS/PT IgM ELISA assays (INOVA Diagnostics, San Diego, CA). According to manufacturer instructions, aPS/PT titers were considered positive when >30 U/mL.
In noAPS group, 8 patients had aPS/PT IgM (42%) while other patients did not have aPS/PT of IgG or IgM isotype (n=11, 58%). In patients with APS, 3 patients had aPS/PT IgG (10.3 %), 6 had aPS/PT IgM (20.7%) and 3 patients had aPS/PT with both isotypes (10.3 %) while 17 had no aPS/PT (58.6 %). In cAPS group, 4 patients had no aPS/PT (13.8 %), 4 patients had aPS/PT IgG (13.8 %), 5 had IgM (17.2 %) and 15 aPS/PT with both IgG and IgM (51.7 %). Proportion of patients with aPS/PT with both isotype was significantly higher in patients with cAPS than in patients with APS without cAPS and patients with stable APL without clinical APS manifestations (p=0.0014 and p<0.0001 respectively using Fisher’s exact test). No difference was observed in the proportion of isolated aPS/PT IgG or IgM between cAPS and APS patients or patients with patients with stable APL without clinical APS manifestations. The 3 patients with APS with aPS/PT with both isotypes developed adrenal insufficiency, cerebral venous thrombosis and Budd-Chiari syndrome.
Our data indicate that presence of aPS/PT of both IgG and IgM isotypes may be associated with severe features of APS, especially cAPS.
Disclosure: M. Miyara, None; L. Arnaud, None; L. Dufat, None; M. C. Diemert, None; A. Ankri, None; A. Mathian, None; J. Haroche, None; D. Boutin, None; P. Ghillani-Dalbin, None; N. Costedoat-Chalumeau, None; S. Casas, None; J. C. Piette, None; L. Musset, None; Z. Amoura, None.