Use of the prewarm method for detecting clinically significant alloantibodies in the presence of cold autoantibodies

The prewarm (PW) method is useful for detecting and identifying clinically significant antibodies that bind to red blood cells and complement at 37°C and for avoiding antibodies that bind at temperatures less than 37°C. Antibodies that bind at temperatures less than 37°C are often cold autoantibodies that may be present in the serum of healthy individuals and are usually not clinically significant. The PW method is useful when these cold autoantibodies have a wide thermal range and interfere with standard testing methods by reacting at the 37°C and antihuman globulin test phases. When using the PW method, it is important to identify underlying, potentially clinically significant alloantibodies during pretransfusion testing to ensure the most appropriate component will be selected for transfusion. Immunohematology 2018;34:148–150.