Desialylation unmasks HPA-9B alloantibodies

In this issue of Blood, Zhang et al1 report new insight into the role of sia-lyation of glycoprotein (GP) IIb for the detection of maternal alloantibodies (to human platelet antigen [HPA]-9b and HPA-3a). These findings are important for fetal/neonatal alloimmune thrombocytopenia (FNAIT) and extend their previous studies on FNAIT.2 By use of designed induced pluripotent stem cells (iPSCs) differentiated to megakaryocytes (MKs) expressing HPA variants of interest, they elegantly provide data showing maternal alloantibodies in sera can be either sialylation dependent or inde-pendent, and that desialylation of glycan chains in close proximity to the allovariant residues has the potential to enhance antibody detection and reveal alloantibodies otherwise missed.