Isohemagglutinin titration in pooled and apheresis platelets

Area of Science:

• Transfusion Medicine
• Immunology
• Hematology

Background:

• Platelet inventory limitations often require ABO-incompatible transfusions.
• Low titre (LT) donor isohemagglutinins testing is costly and performed to minimize hemolytic reactions.
• Pathogen-reduced platelets (PRP) in platelet additive solutions (PAS) dilute plasma, potentially reducing high-titre (HT) isohemagglutinins.

Purpose of the Study:

• To determine the proportion of HT platelets and ABO-incompatible transfusions.
• To reassess the necessity of isohemagglutinin titration following the introduction of PRP/PAS.

Main Methods:

• Manual tube titration (1:50 dilution) of platelet supernatant against A1/B red cells.
• Testing of 49,058 pooled and 11,738 apheresis platelets over 4 years.
• Determination of HT proportion, out-of-group transfusion rates, and hemolytic reactions.

Main Results:

• 60,796 platelet units were tested; HT proportions were 6.6% for group O pooled and 5.7% for group B apheresis platelets.
• 2% of group A pooled and apheresis platelets had HT.
• Approximately 25% of transfused platelets were ABO-incompatible, with no reported hemolytic reactions.

Conclusions:

• Rare platelet pools may exhibit HT, but PRP with PAS significantly reduces titres.
• Titration may become unnecessary with PRP/PAS implementation.
• Group-specific or group A PRP platelet transfusions are proposed as safe alternatives.