Neonatal alloimmune neutropenia associated with maternal anti-HLA antibodies: a conservative interpretation of a rare presentation

Summary

Neonatal alloimmune neutropenia (ANN) is a rare cause of neutropenia in newborns, resulting from maternal antibodies directed against paternal antigens present on fetal neutrophils, in a mechanism similar to Rh haemolytic disease.We present the case of a full-term newborn with severe neutropenia from birth (nadir 110/µL) but no clinical signs of infection. As neutropenia persisted beyond the neonatal period, an immunological study was performed, identifying maternal IgG anti-human leukocyte antigen (HLA) class I and II antibodies and positive cross-match tests against paternal and neonatal neutrophils. While these findings suggest anti-HLA antibodies likely contributed to the neutropenia, the absence of glycoprotein-specific confirmatory assays-such as MAIGA (monoclonal antibody immobilisa