Estrogen and Progesterone Receptors in Breast Cancer Microsamples Simultaneously Quantified by Enzyme-Ligand Immunoassay

A new method (enzyme-ligand immunoassay, ELlA) is de-scribed for the estimation of estrogen (ER) and progester-one (PR) receptors in microsamples of human breast can-cer tissue. The technique, based on the nonisotopic measurement of receptor-bound estradiol and progester-one, involves three steps: (a) simultaneous saturation of active receptors with their respective authentic ligands, (b) heat treatment of the cytosol to release the steroids from theircognatereceptorsbeforeorafterabsorptionwithdex-tran-coated charcoal, and (c measurement of both steroids present in the cytosol by a modified competitive-inhibition enzyme immunoassay. The useful range of the method was 10-4000 pmol/L for ER and 6.5-1000 pmol/L for PR. The correlation coefficient (,) between the one-point and Scatchard plot analysis was 0.95 for ER and 0.99 for PR