Barbati C, et al. - Via 38 primary antiphospholipid syndrome (PAPS, a condition defined by the occurrence of thromboembolic events and/or pregnancy loss combined with presence of circulating antiphospholipid antibodies) subjects (15 patients carrying only antiphospholipid antibodies without clinical criteria of antiphospholipid syndrome (APS) (aPL carriers) and 20 normal healthy subjects), the researchers intended to determine the potential link of anti-D4GDI antibodies with thrombocytopenia in vitro in primary APS. Anti-D4GDI antibodies in sera from 18/38 patients with PAPS, in sera from 2/15 aPL carriers were recognized. A marked 30% rise in the activation of integrin αIIbβ3 upon stimulation of platelets from healthy donors preincubated with the antibody anti-D4GDI filtered from the serum of APS patients was observed. Hence, antibodies anti-D4GDI was discovered in the sera of PAPS patients and it could trigger platelet activation, demonstrating, at least in part, the pro-thrombotic state and the thrombocytopenia of PAPS patients. Moreover, these conclusions could point towards enhanced diagnosis and treatment of APS.