Tris-HCL buffer pH 9.5 mixed with 5% urea used for antigen retrieval immunohistochemistry

Abstract

The antigen retrieval (AR) method plays an important role in the high temperature heating AR immunohistochemistry (IHC). It has been demonstrated that the temperature, heating time and pH value of the AR solution are critical factors in determining the effectiveness of AR-IHC(1,2). For example, the intensity of AR-IHC staining of certain antibodies varies greatly according to the pH value of AR solution (2). Although the original discussed metal solution gave good results of AR-IHC (3,4), the potential for toxicity caused concern. A variety of other AR solutions have been tested as possible replacements for the metal solution, in the hope of obtaining better AR-IHC staining results without toxic side effects. Reports include the use of citrate buffer pH 6, urea, and a commercial ‘TUP’ solution. Currently, citrate buffer pH 6 is the most commonly used AR solution. We have posed the question as to whether this is the optimal AR solution for most antibodies used in surgical pathology.