Neonatal alloimmune thrombocytopenia caused by anti-HLA-A24 alloantibodies

Neonatal alloimmune thrombocytopenia (NAIT) occurs as a result of maternal alloimmunization against paternally inherited antigens on foetal platelets. Platelets express platelet specific antigens (HPA) along with human leucocyte antigens (HLA) class I. Although anti-HLA class I antibodies are often detectable in pregnant women, their role in NAIT is considered controversial. We report a case of NAIT where the most sensitive serological analysis and molecular methods could not detect platelet specific antibodies. Only HLA incompatibility and presence of anti-HLA-A24 antibodies in both the mother's and the newborn's serum were proven. Conclusion: This case supports the idea that some anti-HLA class I antibodies could cause NAIT.