Determination of <scp>IgG1</scp> and <scp>IgG3</scp> subclasses of red blood cell antibodies: An important tool for predicting harmfulness

IgG subclass determination provides diagnostic value beyond IgG quantification alone. In DAT-positive donors, not detecting IgG1/IgG3 is compatible with a low haemolysis risk and often obviates follow-up; when IgG1/IgG3 are detected, selective evaluation may be appropriate. For alloantibodies, subclass identification may help predict clinical relevance, especially in urgent transfusion settings when MMA is unavailable, supporting transfusion safety decisions and efficient resource use.