We encountered a case of neonatal alloimmune thrombocytopenia (NAIT) due to anti-HLA-B7+B60+B61. Bilateral cephal hematoma and umbilical hematoma were noted at eh time of birth. Purpura developed at the third day. Platelet count was 110,000 at
birth and
decreased to 66,000/uL at the day 4. Prothrombin time and partial prothrombin time were within normal limit. The mother's platelet count was 220,000/uL and she had no history of abnormal bleeding. Platelet antibody tests empolying mixed passive
hemagglutination and immunofluorescence revealed that the mother's serum was reactive against the platelets from the father and the neonate, but was not reactive with her own platelets. Platelets from eight volunteer group O donors were tested
with
the
mother's serum; seven were reactive and one was negative. The positive reactions were lost after chloroquine treatment of platelets. Antigen capture ELISA(ACE) and modified antigen capture ELISA employing monoclonal antibodies against platelet
glycoproteins IA, IIb, and IIIa were negative. Mother's serum was tested for lymphocytotoxicity against 49 donor lymphocytes and the specificity was found to be anti-HLA-B7+B60+B61. At the 9th day, one unit of platelet concentrate from the mother
was
transfused and the platelet count of the neonate rose up to 340, 000/uL. The neonate was discharged at the day of sixteenth and the platelet count remained high thereafter.
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