Antigen retrieval for immunohistochemistry status and need for greater standardization

Antigen retrieval (AR) describes a high-temperature unmasking method as well as a nonheating method that is utilized prior to immunohistochemical staining of fixed tissue sections with the goal of improving the quality of the resulting stain. The high-temperature method has been applied extensively to formalin-fixed paraffin-embedded tissue sections, the materials most commonly available to the surgical pathologist. Following the introduction of AR in 1991, there have been numerous articles demonstrating the value of this method for routine immunohistochemistry. More than 200 antibodies have been tested, with excellent immunohistochemical staining in almost all instances. The principles of the AR technique are reviewed, and emphasis is placed on standardization and current application.