ANDROGEN RECEPTOR IMMUNOSTAINING AND ITS TISSUE DISTRIBUTION IN FORMALIN-FIXED, PARAFFIN-EMBEDDED SECTIONS AFTER MICROWAVE TREATMENT

We used microwave (MW) oven heat treatment to unmask human androgen re ceptor (AR) immunostaining in formalin-fixed, paraffin-embedded tissue . Prostate tissue was used as an AR-positive control. Tissue sections were boiled in citrate buffer in a conventional MW oven for 30 min, fo llowed by immunostaining with a validated murine monoclonal antibody ( MAb), F39.4.1, raised against a peptide included in the N-terminal dom ain of the 100 KD human AR. AR immunostaining was localized to the nuc lei of prostate secretory epithelial cells but was weak or absent in b asal cells and of variable intensity in the stromal cells. Slides expo sed to less than 10 min of MW heat treatment or none at all manifested no AR immunoreactivity. Tissue morphology was well preserved. Immunoh istochemical determination of AR status in a wide variety of human tis sues was consistent with that previously reported by others using froz en sections. MW heat treatment of tissue samples is an excellent metho d of localizing AR antigenicity, enabling immunohistochemical evaluati on of AR status in formalin-fixed, paraffin-embedded material.