IMPROVED ANTIGEN RETRIEVAL IN FORMALIN-FIXED, PARAFFIN-EMBEDDED TISSUES

Immunohistochemical techniques have achieved wide-spread utilization, but many potentially useful antigens have been difficult to detect in formalin-fixed, paraffin-embedded tissues. Recently, a number of laboratories have shown that some antigens thought to be destroyed by fixation could be restored to detectability by microwave heating in a buffer solution prior to staining. In this article a large number of solutions over a broad range of pH are examined. The results confirm that 0.1 M citrate buffer, pH 6, and 3 M urea are effective in this context, but demonstrate that 0.5 M Tris base buffer, pH 10, significantly improved staining with some antibodies. The mechanism for the microwave effect remains unknown, but the effectiveness of this basic buffer suggests that continued exploration of these variables may be important to optimize these procedures.