Glycoprotein V is a relevant immune target in patients with immune thrombocytopenia

Abstract

Platelet autoantibody-induced platelet clearance represents a major pathomechanism in immune thrombocytopenia (ITP). There is growing evidence for clinical differences between anti-glycoprotein IIb/IIIa and anti-glycoprotein Ib/IX mediated ITP. Glycoprotein V is a well characterized target antigen in Varicella-associated and drug-induced thrombocytopenia. We conducted a systematic study assessing the prevalence and functional capacity of autoantibodies against glycoprotein V. A total of 1140 patients were included. In one-third of patients, platelet-bound autoantibodies against glycoproteins Ib/IX, IIb/IIIa, or V were detected in a monoclonal antibody immobilization of platelet antigen assay; platelet-bound autoantiglycoprotein V was present in the majority of samples (222 out of 343, 64.7%). Investigation of patient sera revealed the presence of free autoantibodies against glycoprotein V in 13.5% of these patients by an indirect monoclonal antibody immobilization of platelet antigen assay, but in 39.6% by surface plasmon resonance technology. These antibodies showed significantly lower avidity (association/dissociation ratio 0.32±0.13 vs. 0.73±0.14; P