FLOW CYTOMETRIC METHOD FOR THE MEASUREMENT OF EPIDERMAL GROWTH-FACTORRECEPTOR AND COMPARISON WITH THE RADIO-LIGAND BINDING ASSAY

A method for the purification, conjugation, and use of EGF-R antibody 60 quantify EGF receptors on tumour cells by flow cytometry is describ ed. The quantification of both internal and external EGF receptors was determined by treatment with saponin, rendering the cells permeable 6 0 the EGF-R antibody. Using QCS bead standards, the number of EGF-R bi nding sites per cell was assessed. Results were compared with conventi onal EGF-R quantification using a radio-ligand binding assay. A high d egree of correlation was found between the two methods. The flow cytom etric method for EGF-R quantification described is sim-ple, rapid, and reproducible. The assay may be of particular value in measuring EGF-R on urgent clinical samples or those that are too small (such as breas t aspirates) for measurement by the radio-ligand binding assay. Advant ages of this assay over the radio-ligand binding assay include reducti on in use of radio-labelled iodine compounds, a decrease in analysis t ime, and reduced cost and quantity of material needed for assay. In ad dition, flow cytometry offers the possibility of selecting cell phenot ypes by gating as well as live/dead cells by using multi-parameter flo w cytometry. (C) 1994 Wiley-Liss,Inc.