Wolf D. Kuhlmann
The localization of many antigens can be often improved by pretreatment of tissue sections with so-called antigen-retrieval reagents and by physical means such as heat. The antigen-retrieval reagents are thought to break the protein cross-links which have formed by formaldehyde fixation and thereby uncover hidden antigenic epitopes. The techniques involved include combinations of special retrieval solutions with different pH and heat (HIER),e.g. microwave assisted retrieval, or proteolytic-induced epitope retrieval (PIER). Sonication-induced epitope retrieval (SIER) has also been reported.