Current Anti-HPA-1a Standard Antibodies React with the β3 Integrin Subunit but not with αIIbβ3 and αvβ3 Complexes.

Background:  Fetal/neonatal alloimmune thrombocytopenia (FNAIT) results from maternal alloantibodies (abs) reacting with fetal platelets expressing paternal human platelet antigens (HPAs), mostly HPA-1a. Anti-HPA-1a abs, are the most frequent cause of severe thrombocytopenia and intracranial hemorrhage (ICH).

Objectives:  Titration of anti-HPA-1a in maternal serum using standard National Institute for Biological Standards and Control (NIBSC) 03/152 is one diagnostic approach to predict the severity of FNAIT.