Histochemical studies with a monoclonal antibody raised against a partially purified soluble estradiol receptor preparation from human myometrium

A monoclonal antibody (D5) raised against affinity-purified cytosol estradiol receptor (REC) from human myometrium has been used to stain human tissues by means of an indirect immunoperoxidase method. Good staining was obtained with ethanol-, glutaraldehyde-, or Carnoy's-fixed material but not with formalin or Bouin's fixation. Cytoplasmic staining of human breast tumors exhibited a highly significant correlation (P less than 0.001) with REC assayed by conventional estradiol-binding assay provided that allowance was made for both staining intensity and cellularity of the tumor; no correlation existed with soluble progesterone receptor content. Both patient age and tumor differentiation influenced staining patterns in the same way as did REC content. Cultured REC-positive human breast tumor cell lines (MCF-7, ZR-75-1, and CA-2) showed positive staining as did cultured epithelium from human milk. Epithelia in normal breast and fibroadenoma exhibited variable staining that rarely reached the intensity seen in REC-positive tumor cells. The staining patterns of human normal endometrium, myometrium, fallopian tube, ectocervix, endocervix, and ovary and neoplastic endometrium and ovary are described. In every situation thus far examined only cytoplasmic staining has been observed.