Controversy: HLA Antibodies Responsible for Fetal/Neonatal Alloimmune Thrombocytopenia – an Update

Abstract

This review focuses on reports and data dealing with an association between an alloimmunization against HLA class I antigens and fetal/neonatal alloimmune thrombocytopenia (FNAITP) that have been published since 2000. Current serological requirements for a presumed diagnosis of FNAITP in newborns are presented to understand the hesitation towards a diagnosis of HLA antibody- associated FNAITP. Three already published case reports are extensively discussed, and data from 3 series of presumed FNAITP are presented. Furthermore, the data on light chain restriction of such HLA antibodies are discussed in view of a possible clonality of these antibodies in presumed FNAITP.

Neonatal alloimmune thrombocytopenia and neutropenia associated with maternal human leukocyte antigen antibodies

“…For that reason, demonstration of anti‐HLA alloantibodies in both mother and infant is insufficient to determine causality. Some case reports implicating HLA antibodies as a cause for NAIT may in fact be due to certain HPA antigens recently discovered to be rare causes of NAIT 16. Anti‐HPA‐15 has been recently identified as an additional cause for NAIT, though detected in less than 5% of mothers with affected offspring 17.…”

Perinatal Transfusion Medicine – Immunological Aspects

“…However, most platelet immunologists hesitate towards a diagnosis of HLA class I-induced FNAITP even if these are the only detectable antibodies. Panzer [3] summarized the diagnostic requirements for an 'assumed' diagnosis of 'classical' platelet-specific, antibody-induced FNAITP and illustrated why the controversy on an HLA antibody-induced FNAITP is still ongoing. In 1-2% of all pregnancies, recurrent spontaneous abortions occurs.…”