What are the limitations of antibody screening tests?

Updated: Jun 24, 2019
  • Author: Ashok Tholpady, MD, MSc; Chief Editor: Jun Teruya, MD, DSc, FCAP  more...
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Warm autoantibodies are IgG immune responses to a patient's own RBCs, and they are optimally active at 37°C. These warm autoantibodies can be particularly problematic, because they commonly react equally with all reagent cells tested and mask the underlying clinically significant alloantibodies. Further testing such as autoabsorption may be required to remove autoantibodies and to allow identification of other clinically significant antibodies.

Cold autoantibodies are of IgM type, and they are generally considered clinically insignificant, because they do not always cause hemolysis in vivo. However, cold autoantibodies are troublesome in that they can interfere with the detection of clinically significant antibodies. Usually, cold antibodies are easy to spot because of their strong reactions to reagent cells during the immediate spin phase but weaker response during the anti-human globulin (AHG) phase. However, in some cases, they are bound tightly to RBCs, resulting in positivity during AHG. To minimize the chances of this occurring, the plasma or serum sample and screening cells should be prewarmed to prevent binding from occurring.

Nonspecific antibodies may skew the results of antibody screening. These antibodies are not related to RBC antigens; instead, they can occur from other sources, such as underlying diseases and medications.

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