A Case of Neonatal Alloimmune Thrombocytopenia Due to Anti-HLA B44

Neonatal alloimmune thrombocytopenia(NAIT) is a rare disease caused by maternal alloimmunization against fetal platelet surface antigen, which is mainly platelet specific alloantigen or human leukocyte antigen(HLA). During routine hemotology, we accidentally discovered thrombocytopenia in a female fullterm newborn admitted due to jaundice. We excluded NAIT due to human platelet alloantigen(HPA), because the HPA of the mother and baby were the same on PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism). Mother's serum was tested for lymphocytotoxity against 36 donor lymphocytes, and anti-HLA A2, A24 and B58 were found. HLA typing of the father and baby revealed A2 antigen which was not present on the mother's lymphocytes. The patient received concentrated platelet and intravenous globulin. Her platelet count increased to 222,000/mm from 3,000/mm on the 11th day of life. We described a case of NAIT due to anti-HLA A2 antibody with a detailed clinical feature. (J Korean Pediatr Soc 1999;43:861-865)