Evaluation of flow-cytometric three-parameter analysis for EGFR quantification and DNA assessment in human bladder carcinomas

 Flow-cytometric multi-parameter staining is an excellent method for defining tumour subpopulations. This provides further understanding of tumour heterogeneity and defines the biological relevance of tumour subpopulations. A method of quantifying the epidermal growth factor receptor (EGFR) in parallel with DNA staining, which was previously established in bladder carcinoma cell lines, was applied to twenty-five biopsies of urothelium and urothelial neoplasms. Uro5, a surface glycoprotein, was used to identify urothelial cells. Objective quantification of receptor content via flow cytometry was achieved with beads of defined numbers of antigen-binding sites, and receptor numbers obtained from urothelial and nonurothelial cells were compared with staining intensity in a three-step immunoperoxidase detection of the EGFR. The data obtained matched the immunohistochemical findings and were more sensitive in the low range (ca. 5×103) of receptors. Parallel definition of the proliferative fraction and DNA-ploidy of tumour cells means that this method satisfies the requirements of objective quantification for oncological diagnosis.