Platelet glycoprotein complex Ia/IIa antibodies cause neonatal alloimmune thrombocytopenia but do not inhibit megakaryopoiesis and platelet recovery after allogeneic cord blood stem cell transplantation.

A sibling cord blood (CB) transplantation was performed in a boy with Wiskott-Aldrich syndrome. The CB (31 x 10(6) CD34(+) cells) derived from a newborn sister with neonatal alloimmune thrombocytopenia (NAIT) with 40,000 platelets/microl, caused by a maternal anti-HPA-5b and HLA-A2 antibody. Maternal serum did not inhibit clonogenicity after in vitro testing of megakaryopoiesis. Accordingly, this CB was accepted for sibling transplantation. The transplantation showed a good course with fast and sustained hematopoietic reconstitution (granulocytes >500/microl on day +16, platelets >50,000/microl on day +30). This case demonstrates a successful CB transplantation from a donor suffering from NAIT.