QUANTITATIVE RADIOIMMUNOHISTOCHEMICAL MEASUREMENTS OF P185(ERBB-2) INFROZEN TISSUE-SECTIONS

The relationship between expression of the c-erbB-2 protooncogene and the biology of breast cancer has been investigated widely, most studie s using immunohistochemistry in formalin-fixed, paraffin-embedded tiss ues. This technique is at best semiquantitative and there is a high de gree of interstudy variability because of its subjective nature and po or methodological standardization. The relationship between the levels of expression and biology can be examined thoroughly only with an acc urately quantitative technique, We have developed a radioimmunohistoch emical assay to measure p185(erbB-2) in tissue biopsy specimens, The m ethod involves incubating frozen sections with I-125-labeled monoclona l antibody, microautoradiograpy, and grain counting with image analysi s, Sections of cell pellets with known c-erbB-2 levels are processed w ith each batch of samples as internal calibration standards. We have q uantified c-erbB-2 expression in 60 breast carcinomas and compared the results with conventional immunohistochemistry. Radioimmunohistochemi stry measured receptor levels throughout the range of expression in br east carcinomas, whereas conventional immunohistochemistry detected th e protein only in the highest expressing tumors, The quantitative, obj ective data produced by radioimmunohistochemistry allow a more thoroug h evaluation of the relationship between c-erbB-2 expression and tumor biology, This technique may have applications in other fields where q uantitative data is required and relevant monoclonal antibodies are av ailable.