Lack of platelet response to collagen associated with autoantibodies against glycoprotein (GP) Ia/IIa and Ib/IX leading to the discovery of SLE

An increased bleeding time and a prolonged APTT (activated partial thromboplastin time) observed in a 48-year-old woman led to the discovery of SLE confirmed by immunological tests. Platelet function and analysis of membrane glycoproteins revealed an isolated impaired collagen induced platelet aggregation and allowed the detection of autoantibodies directed against GpIa/IIa and GpIb/IX.