After clotting, separate serum from cells if specimen is to be stored in refrigerator. Do not refrigerate prior to separation of serum from red cell. Antibiotic therapy may interfere with antibody formation. Cold agglutinins are usually IgM autoantibodies directed against the Ii antigens of human RBCs.
Antibodies reacting near physiologic temperatures are more likely to be clinically important.
Detection of cold agglutinins may be particularly important in patients where cold blood is to be used such as in a blood cardioplegia unit.