Persistent neonatal alloimmune thrombocytopenia caused by triple anti-HLA-A11, -B3901, and -Cw7 antibodies

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is primarily caused by the transplacental passage of maternal antibodies commonly directed against fetal human platelet antigens (HPA) and rarely against human leukocyte antigens (HLA).

Here, we report a case of prolonged neonatal alloimmune thrombocytopenia (NAIT) associated with three anti-HLA antibodies. A male infant was delivered at 37 weeks' gestation because of non-reassuring fetal status. His platelet count decreased to 14 × 10⁹/L on postnatal day 8. A random-donor platelet transfusion and intravenous immunoglobulin were administered without clinical complications. Immunoserological investigations were performed to identify HLA, HPA, and antibodies in the patient and his parents.

Anti-HLA-A11, -B3901, and -Cw7 antibodies, but not anti-HPA antibodies, were identified in the mother's blood that reacted with the lymphocytes of the infant and his father.

Three distinct anti-HLA (HLA-A11, B3901, and Cw7) may have caused the prolonged neonatal thrombocytopenia observed in the present case. This case report demonstrates the role of anti-HLA antibodies in the pathogenesis of FNAIT.