Isohemagglutinin titration in pooled and apheresis platelets

Abstract

BackgroundPlatelet inventory constraints necessitate ABO‐incompatible platelet transfusion. Many minimize the hemolytic impact by confirming low titre (LT) donor isohemagglutinins. This process is costly. Pathogen‐reduced platelets (PRP) in platelet additive solutions (PAS) will dilute plasma and decrease high‐titre isohemagglutinins (HT). We determined the proportion of HT platelets and incompatible transfusions for units suspended in plasma to reassess the need for titres following introduction of PRP/PAS.Study Design and MethodsOur titre method is manual tube (1:50) dilution of platelet supernatant from apheresis or whole blood derived buffy coat pools suspended in plasma, tested with A1/B red cells. Testing included 49,058 pooled and 11,738 apheresis platelets over 4 years. The HT proportion, rate of out‐of‐group transfusions, and hemolytic reactions were determined. The impact of PAS dilution was estimated.ResultsTotally 60,796 platelet units were tested. Group O pooled and group B apheresis platelets had HT in 6.6% and 5.7%, respectively. Group A pooled and apheresis platelets included 2% with HT. Approximately 25% of platelets transfused were ABO‐incompatible and no hemolytic reactions were reported. Based on the proportions of PAS‐E and plasma for PRP platelets, plasma from each donor comprises 11 mL (6% of total volume) vs 20‐257 mL in untreated pools. PAS‐E will replace and dilute residual plasma by at least 50%.DiscussionRare platelet pools may demonstrate HT. PRP platelets with PAS will reduce titres and may abrogate the need for titration. A strategy of group specific transfusion or transfusion of group A PRP platelet transfusions may be a safe alternative.