LOW-TEMPERATURE ANTIGEN RESTORATION OF STEROID-HORMONE RECEPTOR PROTEINS IN ROUTINE PARAFFIN SECTIONS

The most widely used non-enzymatic method for unmasking antigens prior to immunohistochemical staining is based on immersion of deparaffiniz ed paraffin sections in citrate buffer and exposure to high temperatur e heating (100 degrees C) with a microwave. In our experience, the ben efits of this technique as applied to cytoplasmic proteins does not ro utinely translate to the nuclear estrogen and progesterone receptor (E R and PgR) proteins. The lifting or loss of portions of a breast biops y section can seriously interfere with efficient scoring of invasive t umor cells. The use of low temperature restoration (80 degrees C) in c itrate buffer using a water bath avoids problems of tissue disruption and generally restores the immunoreactivity of ER and PgR proteins in a more uniform fashion than does the microwave approach.