Last update:
07-Jul-2004

Radioimmuoassays, particularly immunoradiometric assays (IRMAs), are vulnerable to interference by various circulating human antibodies. The incidence of such antibodies, iatrogenic and non-iatrogenic causes for their presence, and the mechanism of the encountered interference are discussed in this paper. The interfering antibodies are classified as either heterophile antibodies, including the human anti-animal antibodies (HAAAs), or autoantibodies. The rheumatoid factors belong to the autoantibody class. The methods of detection of these antibodies and various approaches to combat their clinical impact are also discussed. The clinical significance of the antibodies is explored, with special emphasis on the interference encountered in the thyroid function and the tumor marker assays. Finally, practical points for handling this problem are offered, because, if such interference escapes notice, it holds the potential for serious clinical consequences and possible legal repercussions.

Key words: Autoantibodies, Heterophile, Interference, Radioimmunoassays, Rheumatoid factors.