[Comparative studies of estrogen receptor determinations by enzyme immuno-assay using the monoclonal antibody,...

Estrogen receptor (ER) determination in human mammary tumors was performed by enzyme immunoassay (EIA) using monoclonal antibody, and the results were compared with those obtained using the dextran-coated charcoal (DCC) and sucrose density gradient (SDG) method. Twenty ER-positive tumors by the DCC method were all ER-positive by EIA, when determined in the same cytosol fraction. Three out of 21 ER-negative tumors by the DCC method were ER-positive by EIA. Estrogen receptors of 8S, 8S + 4S, and 4S determined by the SDG method were all shown to be ER-positive using EIA. Between the values of estrogen receptors determined by the DCC method and by EIA, a high correlation was observed (r = 0.868). Values of ER less than 13.5 fmol/mg protein were considered as negative ER.