Alloimmune neonatal neutropenia.

In three neonates, the diagnosis of anti-NA1 alloimmune neutropenia related to maternal immunization against fetal polymorphonuclear leukocytes (PMN) antigens was achieved by serum antibody screening and PMN phenotyping. All the children were small for date and exhibited bacterial infection within days 2-13. Neutropenia persisted until days 20-50. High-dose intravenous immunoglobulin G (IVIgG) was ineffective. In one case, NA1-negative PMN collected from a normal donor were infused because of infection after thoracic surgery and resulted in a sharp but transient increase in PMN counts with resolution of infection. The natural history and the management of alloimmune neonatal neutropenia are discussed.