Neonatal allo-immune thrombocytopoenia (NAIT)

Key words: Neonatal allo-immune thrombocytopenia (NAIT), HLA antibodies, Neonatal cytopoenias

Neonatal allo-immune thrombocytopoenia (NAIT) is a pathology caused by the passage of maternal antibodies against fetal platelet antigens through the placenta. The role of platelet-specific antigens of paternal origin (HPA - Human Platelet Antigen) as responsible of allo-immunization is well documented. On the contrary, the importance of HLA antigens expressed on platelets is still matter of debate. As antibodies anti HLA of class I are often in blood of pregnant women, but rarely they are cause of neonatal cytopoenias, the diagnosis is usually by exclusion. The article reports a case of NAIT in which the incompatibility to antigens of HLA system has been documented. Although rare, this type of allo-immunization should be considered in cases of neonatal thrombocytopenia.