LOCALIZATION OF EGF RECEPTORS IN FROZEN TISSUE-SECTIONS BY ANTIBODY AND BIOTINYLATED EGF-BASED TECHNIQUES

We developed a sensitive EGF receptor detection method for frozen tiss ue sections using biotinylated EGF as the primary reagent. The method was directly compared with an immunohistochemical technique based on a n anti-EGF receptor monoclonal antibody (MAb EGFR1) in normal human an d rat tissues and in human tumors. The method was more sensitive than a previously published biotinylated EGF-based technique. In normal hum an tissues and in 37 of the 50 tumors, the binding pattern mirrored th at of positive staining with EGFR1. Five further tumors showed weak im munoreactivity, but in these no binding of biotinylated EGF was detect ed. The remaining eight tumors were negative by both techniques. The d iscordant cases may reflect a lower level of sensitivity of the ligand -binding technique or, alternatively, abnormal receptors may have been expressed in these tissues. EGF receptors could be detected in rat li ver with biotinylated EGF but not with the antibody, indicating the us efulness of the ligand-based technique in cross-species studies.