A new dual immunocytochemical assay for oestrogen receptor (ER) and epidermal growth factor receptor (EGFR) has been developed. It has been tested in a variety of conditions using cell culture lines and the results correlate well with those obtained from single immunocytochemical assays. MCF-7 and A431 cells and a mixture of the two types of cell were assessed immunocytochemically for ER and EGFR. ER showed immunopositivity of 30% in MCF-7 cells, 10% in the mixture and 0% in A431 cells. EGFR demonstrated immunopositivity of 0% in MCF-7 cells, 70% in the mixture and 100% in A431 cells. Dual immunocytochemical assays using anti-ER followed by anti-EGFR monoclonal antibodies on single histological sections showed similar reactivity to the single assays. Three staining patterns were seen in the mixture: ER+/EGFR-(MCF-7 cells), ER-/EGFR-(MCF-7 cells) and ER-/EGFR+ (A431 cells). ZR-75-1 and MDA-MB-231 cells and their retrovirally transfected counterparts ZR/HERc and MDA/HEGO cells were then analysed. The dual assay revealed the fourth phenotype (ER+/EGFR+) in 40% of ZR/HERc cells and in 10% of MDA/HEGO cells. This is the first description of a dual immunocytochemical assay system for ER and EGFR on single 5 μm frozen section samples. Studies are now underway assessing breast carcinoma sections which may allow investigation of the clonality of human breast cancer.

dx.doi.org/10.1007/BF00157763, hdl.handle.net/1765/58575
Histochemical Journal
Department of Pathology

Sharma, A.K, Horgan, J.H, McClelland, R.L, Douglas-Jones, A.G, van Agthoven, A.J, Dorssers, L.C.J, & Nicholson, R.I. (1994). A dual immunocytochemical assay for oestrogen and epidermal growth factor receptors in tumour cell lines. Histochemical Journal, 26(4), 306–310. doi:10.1007/BF00157763