Optimal conditions for the retrieval of CD4 and CD8 antigens in formalin-fixed, paraffin-embedded tissues.

The effects of buffer, NaCl, EDTA, and urea on the retrieval of CD4 and CD8 antigens in formaldehyde-fixed, paraffin-embedded tissues with a microwave pressure-cooker were evaluated. The optimal retrieval conditions were found to be borate buffer at pH 8 containing 1 mM NaCl and 1 mM EDTA. Urea was found to be less effective.

Evaluation of antigen retrieval buffer systems.

The introduction of antigen retrieval (AR) techniques has dramatically improved the sensitivity of immunohistochemical detection of various antigens in formalin-fixed, paraffin-embedded tissues. The microwave-heating and pressure-cooking procedures are the most effective AR methods reported to date. Although extensive efforts have been made to optimize AR procedures using these two methods, previous studies have not led to a standard protocol applicable to all antibodies derived from different clones. In this study we have investigated the optimal AR buffer conditions for 29 antibodies that are in common use for diagnostic purposes in hospitals worldwide. Borate (pH 8.0) and Tris buffer (pH 9.5) yielded the highest retrieved antigen immunoreactivity against most antibodies as compared to other buffers tested. In addition, the microwave pressure-cooking gave better results than microwave-heating alone. Therefore, borate (pH 8.0) or Tris (pH 9.5) buffer used in conjunction with the pressure-cooking procedure is strongly recommended for standard routine use.