Neonatal Alloimmune Thrombocytopenia (NAIT) and Post-Transfusion Purpura (PTP)

The McMaster Platelet Immunology Laboratory provides comprehensive investigation for neonatal alloimmune thrombocytopenia and is the reference laboratory for the Province of Ontario for investigation of alloimmune-mediated platelet disorders1. Investigations include assessment of maternal-paternal/fetal antigen incompatibility and testing maternal serum for the presence of anti-platelet antibody.  Maternal serum is investigated for the presence of maternal platelet alloantibodies to both known and novel platelet antigens using a Human Platelet Antigen glycoprotein-specific EIA and a sensitive immunoprecipitation assay. Paternal platelets are used to identify maternal antibodies to novel or low frequency antigens. PCR methods are used to determine the genotype type of maternal and paternal platelets. Comprehensive testing of fetal samples from amniocentesis is offered. The comprehensive report includes a risk assessment for the diagnosis of NAIT for current and future pregnancies. Patients with transfusion‐related antibodies and those with post‐transfusion purpura are investigated using similar methods.

Test Methods:

  • Genotyping: Maternal/Paternal antigen incompatibility and fetal risk assessment
  • Serology: Glycoprotein-specific‐EIA and Radioimmunoprecipitation
  • Maternal antibody to Human Platelet Antigens and to paternal platelet antigens

Information and Form:


  1. Arnold DM,  Smith JW,  Kelton JG.  Diagnosis and management of neonatal alloimmune thrombocytopenia.  Transfus Med Rev.  2008.