An antibody molecule that recognizes multiple unrelated antigens is defined as polyreactive. Polyreactivity is an intrinsic characteristic of immune repertoires. Degenerated antigen binding diversifies the repertoire of specificities, thus contributing to immune defense and immune regulation. Immune repertoire contains also a fraction of immunoglobulins, which acquire polyreactivity only following contact with various protein-destabilizing or pro-oxidative substances. Posttranslational induction of the antibody polyreactivity may have important repercussion for laboratory practice, as well as in cases of pathological conditions accompanied by liberation of large quantities of pro-oxidative substances such as heme, labile iron, or reactive oxygen species. Antibodies with induced polyreactivity have been demonstrated to exert pathogen neutralization and immune regulatory potential in inflammatory conditions, suggesting that this phenomenon may be exploited for design of therapeutic strategies. In this article, we provide description of the basic procedures for uncovering of the cryptic polyreactivity of antibodies by heme, ferrous ions, and acid pH solution.
Keywords: Acidic pH; Antibody polyreactivity; Cryptic antigenic specificities; Heme; IgG; Immunoglobulins; Iron ions; Natural antibodies.