ABO isohemagglutinin titration or hemolysin test: what should we do to reduce the risk of passive hemolysis?☆

Platelet concentrates from ABO-identical donors are the components of choice for transfusions. Since platelet inventories are generally insufficient and because there is usually a higher frequency of group O donors, perfect matches are not always possible and therefore ABO-incompatible platelet transfusions are an accepted practice when ABO-identical platelets are unavailable.1 However, an acute hemolytic transfusion reaction (HTR) can be a severe complication after this type of transfusion due to the passive transfusion of antibodies from donors possessing unusually high-titers of anti-A and/or anti-B antibodies.2 Reducing the risk of HTRs due to plasma-incompatible platelet transfusions has been generating interest and discussions. Strategies to reduce the risk of platelet-associated HTRs include volume reduction of platelets and screening donor plasma for high titers of antibodies by performing antiA and/or anti-B titration or assays for in vitro hemolysis.1 Methods currently employed to identify high titers of antiA and/or anti-B antibodies include titration by the saline agglutination test, with and without incubation, gel test,