A Case of Neonatal Alloimmune Thrombocytopenia due to Anti-HLA-B35

ABSTRACT

Neonatal alloimmune thrombocytopenia (NAIT) is induced by maternal antibodies to fetal platelet alloantigens. Because the main cause of NAIT is incompatibility to platelet specific antibodies, NAIT due to HLA antibodies are relatively rare. We managed a case of NAIT induced by maternal anti-HLA-B35 antibodies. The patient was a second born male. He had no petechiae or purpura at birth. He was admitted to the hospital due to fever for 5 days and a platelet count of 106x10(9)/L. The fever subsided after admission but on the 2nd day of admission, petechiae developed on the chest wall and the platelet count decreased to 25x10(9)/L. Other laboratory findings included C-reactive protein, prothrombin time, and partial thromboplastin time were normal. His mother's platelet count was normal and she had no history of bleeding. Anti-HLA-B35, B52, B56, C3, and C14 were identified in the mother's serum by a panel reactive antibody test and HLA-B35 antigen was identified in the father's and patient's sera. These finding suggested that maternal Anti-HLA-B35 antibody was a response to neonatal HLA-B35 antigen inherited from the father. The patient received concentrated platelet and intravenous immunoglobulin. The platelet count rose to 248x10(9)/L and was maintained thereafter.