Neonatal Alloimmune Thrombocytopenia Caused by Anti-HLA-A2 Alloantibodies Determined by Luminex Single Antigen Bead Assay

Neonatal alloimmune thrombocytopenia (NAIT) occurs when maternal alloantibodies react to antigens expressed on fetal platelets, which is mainly platelet-specific alloantigen or HLA, resulting in their immune destruction. Here, we described a patient who suffered from NAIT caused by anti-HLA-A2 antibody. Sera from the mother and the newborn were screened for human platelet antigen-specific antibodies and HLA antibodies by ELISA, and HLA antibodies were detected in both of them. The antibody specificity was identified as anti-HLA-A2 by Luminex single antigen bead assay. HLA typing results showed that patient's father descended HLA-A2 antigen on the patient and the mother was HLA-A2 negative. It is most conceivable that anti-HLA-A2 alloantibody in the mother's sera crossed the placenta and subsequently caused NAIT in the case presented. The patient received platelet concentrates, oral steroid and intravenous globulin and platelet count increased to 120x10(9)/L on the 90th day of life. The Luminex single antigen bead assay used in this case is highly sensitive and specific assay to determine antibody specificity and it is faster and more convenient for routine use in clinical laboratory so that this assay could be useful to diagnose NAIT caused by HLA antibodies and treat such NAIT patients with HLA matched platelet transfusion.

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

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.

A Case of Neonatal Alloimmune Thrombocytopenia due to Anti-HLA-B62+B75 / 대한수혈학회지

We encountered a case of neonatal alloimmune thrombocytopenia (NAIT) due to anti-HLA-B62+B75. We incidentally find thrombocytopenia (14,000/uL at birth and decreased to 4,000/uL at 12 hours after birth) in a female fullterm neonate. Petechial skin lesions are developed on her back and buttock at second day of birth. Her mother suffered from preeclamsia during her last trimester, but her platelet count was 167,000/uL and she had no history of abnormal bleeding. Anti-HLA-B62+B75 antibody was identified in mother's serum by panel reactive antibody test and was reactive with father's platelet by mixed passive hemagglutination assay. Platelet concentrate was transfused at the second and 5th days and patient's platelet count rose up to 58,000/uL just after transfusion but decreased to 21,000/uL eventually. From the 8th day, gamma globulin (1g/kg/day) was started intravenously for 3 days and platelet count rose up to 128,000/uL at 13th day and remained within normal limit thereafter.

A Case of Neonatal Alloimmune Thrombocytopenia dut to Anti-HLA A2

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 lyrnphocytotoxity 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 mothers 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)