How Does Antigen Retrieval Work?Leong, Trishe Y-M. MB, BS (Hons), FRCPA, FCAP*; Leong, Anthony S-Y. MB, BS, MD, FRCPA, FRCPath, FCAP, FASCP, FHKAM (Pathol), Hon FRCPath, Hon FRCPT†Advances in Anatomic Pathology: March 2007 - Volume 14 - Issue 2 - p 129-131 doi: 10.1097/PAP.0b013e31803250c7 Review Articles Buy Abstract Author InformationAuthors Article MetricsMetrics The introduction of antigen retrieval has enabled immunohistology to become an integral component of morphologic diagnosis, routinely employed in cancer diagnosis, and for the identification of therapeutic and prognostic markers. The mechanism of antigen retrieval, however, remains speculative with the key to our understanding embedded in the actions of formaldehyde on proteins. One commonly held concept is that heat primarily breaks down protein cross-linkages that occur with aldehyde fixation, thus “unmasking” protein epitopes of interest. Enzymatic pretreatment is also thought to have a similar action whereas such “breakages” are the result of extremely rapid molecular movement induced by microwaves and ultrasound. The formation of rigid cagelike calcium complexes during formaldehyde fixation is another suggested mechanism of antigen masking requiring chelating agents for reversal. A more recent suggestion for the antigen retrieval phenomenon has evoked the Mannich reaction, which occurs with the cross-linking of some proteins. Such cross-linkages can be hydrolyzed by heat or alkalis so that the process of antigen retrieval may be the simple removal of such cross-linked proteins that are sterically interfering with the binding of antibodies to linear protein epitopes in the tissue section. We are clearly not yet in possession of all the answers to the problem. *Victoria Cytology Service, Melbourne, Victoria †Hunter Area Pathology Service, Newcastle, NSW 2310, Australia Reprints: Professor Anthony S-Y. Leong, MD, PhD, Hunter Area Pathology Service, Locked Bag 1, HRMC, Newcastle 2310, Australia (e-mail: email@example.com). © 2007 Lippincott Williams & Wilkins, Inc.