Low-frequency human platelet antigens as triggers for neonatal alloimmune thrombocytopenia.

Background: Twenty-four low-frequency human platelet antigens (LFHPAs) have been implicated as immunogens in neonatal alloimmune thrombocytopenia (NAIT). We performed studies to define more fully how often these antigens trigger maternal immunization leading to NAIT.

Study Design And Methods: In a Phase 1 study, fathers of selected NAIT cases not resolved by serologic testing but thought to have a high likelihood of NAIT on clinical and serologic grounds were typed for LFHPAs by DNA sequencing.

A point mutation in the EGF-4 domain of β(3) integrin is responsible for the formation of the Sec(a) platelet alloantigen and affects receptor function.

Neonatal alloimmune thrombocytopenia (NAIT) is caused by fetomaternal platelet incompatibility with maternal antibodies crossing the placenta and destroying fetal platelets. Antibodies against human platelet antigen-1a (HPA-1a) and HPA-5b are responsible for the majority of NAIT cases. We observed a suspected NAIT in a newborn with a platelet count of 25 G/l and petechial haemorrhages.

New platelet glycoprotein polymorphisms causing maternal immunization and neonatal alloimmune thrombocytopenia.

Background: Maternal immunization against low-frequency, platelet (PLT)-specific antigens is being recognized with increasing frequency as a cause of neonatal alloimmune thrombocytopenia (NAIT).

Study Design And Methods: Serologic and molecular studies were performed on PLTs and DNA from two families in which an infant was born with severe thrombocytopenia not attributable to maternal immunization against known PLT-specific alloantigens.

Results: Antibodies reactive only with paternal PLTs were identified in each mother using flow cytometry and solid-phase assays.

New low-frequency platelet glycoprotein polymorphisms associated with neonatal alloimmune thrombocytopenia.

Background: Recent reports suggest that maternal immunization against low-frequency, platelet (PLT)-specific glycoprotein (GP) polymorphisms is a more common cause of neonatal alloimmune thrombocytopenia (NATP) than previously thought.

Study Design And Methods: Serologic and molecular studies were performed on PLTs and DNA from three families in which an infant was born with apparent NATP not attributable to maternal immunization against known PLT-specific alloantigens.

Results: Antibodies reactive only with paternal PLTs were identified in each mother.