Neonatal Alloimmune Thrombocytopenia Caused by an Antibody to the Bak^a Antigen

Abstract

A 31 year old woman was assessed following delivery of her second child affected by neonatal alloimmune thrombocytopenia (NAIT). Antiplatelet antibodies with specificity for Bak^a were identified in the woman's serum and her platelets were typed as Bak^a negative whilst her husband's were Bak^a positive. Unlike the majority of reported anti-Bak^a antibodies in the literature, this patient's serum contained no contaminating anti-HLA antibodies. This is the first report of NAIT caused by an anti-Bak^a without co-existing anti-HLA antibodies. An anti-Bak^a antibody has not previously been reported in Australia. The current status of this antigen system is reviewed.

Key Words:

• Neonatal alloimmune thrombocytopenia
• antiplatelet antibodies
• Bak^a