An update on the immunohistochemical localization of estrogen receptors in mammary carcinomas utilizing polyclonal anti-receptor antibodies.

An immunohistochemical (IF) method utilizing polyclonal antibodies to cytoplasmic estrogen receptors (ER) and a tissue processing procedure which allows in situ precipitation of cytoplasmic ER without denaturation of antigenic sites were first described in this journal. In this report we present data on the immunohistochemical classification of 153 cases of human breast carcinomas (123 frozen sections, 28 cytological specimens) as ER-positive (IF+) or ER-negative (IF-). Results on correlation between the biochemical vs immunohistochemical assessment of the ER status and the relationship between quantity of ER and the proportion of IF+/IF- tumor cells are presented. In addition, a procedure which has been successfully applied to study in vitro translocation of cytoplasmic ER in cryostat sections of human breast carcinomas is described. A positive correlation between ER translocatability and status of progesterone receptors (PR) was obvious. All biochemical and immunohistochemical data are collectively reviewed and the question of whether the antibodies are detecting Type I ER is examined.