Nonspecific staining in the immunolocalization of estrogen receptors

An immunohistochemical study of steroid binding by endometrial glandular epithelial cells throughout the menstrual cycle

An immunohistochemical technique was used to demonstrate oestrogen and progesterone binding by endometrial glandular epithelial cells at various stages of the menstrual cycle. A cross-section of steroid binding sites, including low affinity, concentration dependent Type II and III binding sites, were demonstrated but only in cells which contain the classical high affinity receptor. The technique demonstrated both free binding sites and receptor-hormone complexes within the cytoplasm but was poorly effective in demonstrating nuclear complexes. Oestrogen binding sites were shown to reach a peak during the late proliferative and early secretory phases of the cycle: oestrogen binding capacity remained high during the mid and late secretory phases. Progesterone binding capacity rose progressively throughout the proliferative and early secretory phase.

An immunohistochemical study of the incidence and significance of human gonadotrophin and prolactin binding sites in normal and neoplastic human ovarian tissue

An immunoperoxidase technique has been utilised for the demonstration of follicle stimulating hormone (FSH), luteinising hormone (LH) and prolactin (PRL) binding sites in normal human ovaries and in a wide range of benign and malignant epithelial tumours of the ovary. The incidence of FSH, LH and PRL binding was, respectively, 32%, 41% and 39% in normal ovaries, 30%, 18.5% and 22.5% in benign epithelial tumours and 51%, 32% and 43% in malignant epithelial neoplasms. The incidence of FSH binding was significantly higher in malignant epithelial neoplasms than in either normal ovaries or benign epithelial tumours but otherwise no correlation was found between hormone binding capacity and the degree of malignancy of epithelial ovarian tumours, the histological type of the tumour, the degree of differentiation of the malignant epithelial tumours or the presence or absence of metastatic disease. Well differentiated malignant tumours did, however, tend to stain more strongly than did poorly differentiated neoplasms, thus suggesting that the number of binding sites per cell tends to decrease with decreasing degrees of differentiation.

Immunocytochemical localization of tissue-bound oestradiol in rat paracervical ganglion

The uterine paracervical ganglion (Frankenhauser's ganglion) contains the terminal neurons of the cholinergic sacral parasympathetic, the short adrenergic sympathetic and the peptidergic (vasoactive intestinal polypeptide-containing) nerves of the internal genitalia. Previous studies have shown that either the number of cells or transmitter content of each of these neuronal systems is altered by variations in steroid hormones. Furthermore, our recent study showed that some component of the rat paracervical ganglion was capable of metabolizing [3H]oestradiol to oestrone and the 2-OH and 4-OH forms of oestrone and oestradiol. The present study employs the peroxidase-anti-peroxidase immunohistochemical method to localize oestradiol in rat paracervical ganglia. Specific reaction product was identified in (1) cytoplasm and some nuclei of principal ganglion cells, (2) cytoplasm of large vacuolated ganglion cells, (3) cytoplasm of 'small intensely fluorescent' cells and (4) some nerve fibres in ganglia from animals in oestrus. The cytoplasm of principal neurons and some nerve fibres exhibited specific staining for oestradiol in dioestrus and pro-oestrus. No oestradiol was localized in ganglia excised from animals in metoestrus. Preincubation in oestradiol before fixation was necessary for specific localization of oestradiol; treatment of tissues with oestradiol after fixation was not required. These results are not consistent with binding of oestradiol to the classical oestrogen receptor. The resistance of oestradiol to organic solvent extraction suggests that oestradiol is covalently bound to tissue proteins. Such covalently bound oestradiol has been reported as a by-product of tissue metabolism of oestradiol via P-450 enzymes.

Immunohistologic localization of estrogen receptors in breast cancer with monoclonal antibodies. Correlation with biochemistry and clinical endocrine response

Breast cancer specimens from 114 patients were assayed for the presence of estrogen receptors (ER) utilizing highly specific, monoclonal antiestrophilin antibodies and the peroxidase-antiperoxidase technique. Results were compared with conventional ER determinations by the dextran-coated charcoal method (DCC) and were in agreement as to positivity and negativity in 86%. Semiquantified immunocytologic assay results were in accord with the level of ER as measured by DCC in 66%. The tumors studied included 43 from patients with Stage IV disease where clinical response to hormonal manipulation was known. In the latter group, the immunohistologic method had a sensitivity similar to that of DCC but showed a superior positive predictive value and a significantly better specificity. These results indicate that this new method is a valuable laboratory tool, enabling prediction of hormone responsiveness in advanced mammary carcinoma and capable of performance at the community hospital level.

Oestrogen receptor assay of cryostat sections of human breast carcinomas with simultaneous quantitative histology

Cryostat sections of unfixed human breast carcinomas were assayed for oestrogen receptor (ER) content using an isoelectric focusing method to separate the receptor-bound oestradiol. Adjacent sections from the same tissue block were stained so that the tumour content could be estimated by point counting and the ER concentration adjusted to compensate for variations in cellularity. Elastosis was also assessed. The results confirm a positive correlation between ER values and both cellularity and elastosis. The measurement of ER in cryostat sections is relatively simple and rapid, is applicable to small tissue samples, and permits histological identification of the nature and composition of the assayed sample. The method is directly applicable to oestrogen receptor analyses of breast carcinomas in clinical laboratories with facilities for cryostat microtomy.

Are fluorescein-conjugated androgens appropriate for a histochemical detection of prostatic androgen receptors?

Histochemical fluorescence techniques could be of great value in order to assay androgen receptors (AR), particularly in punch biopsies from human prostatic carcinoma (PCA). Therefore, prostatic tissue was examined for specific binding of fluorescein-labeled 5 alpha-dihydrotestosterone derivatives (FDHT) to AR. Using a 17 beta-fluoresceinated DHT derivative (17-FDHT), variable fluorescence was found in human and rat prostates at high 17-FDHT concentrations. This fluorescence could be blocked by unlabeled DHT in 11 and 73% of human and rat prostatic tissue, respectively. Control studies of receptor and organ specificity were conducted and showed that preheated slices from rat prostates displayed no decrease of fluorescent staining. No difference in fluorescence intensity could be seen between prostates from castrated and uncastrated rats. Unstained tissue slices frequently showed a considerable intensity of autofluorescence. An appreciable amount of fluorescence in both rat liver and spleen was found. From these results and various general methodical problems inherent in fluorescent receptor assays, we conclude that the fluorescence techniques described are inappropriate for demonstration of AR.

Immunohistologic and histochemical methods for detection of steroid binding in breast cancer: a reappraisal

A review of the current literature on immunohistologic and histochemical methods for the detection of steroid hormone binding sites in breast cancer, reveals that many, but not all of the criteria for establishing hormone-receptor binding interactions have been met. These include tissue specificity, binding between labeled ligands and soluble receptor in vitro, correlations between histochemical and biochemical assays, as well as between histologic procedures and tumor hormone responsiveness. However, histochemical binding phenomena do not appear to follow classical receptor dogma in regard to the concentration of ligand required, or specificity of binding as determined by competitive binding assays. It is concluded that these histologic techniques may be detecting classical receptor that may be reacting differently than would be expected from biochemical analyses, Types II and III binding sites, and/or organelle and membrane-bound receptors. Certainly no current method should presently be promoted as a laboratory method for the detection of classical receptor. New immunocytologic procedures employing specific, antireceptor sera currently under development, may obviate many of the criticisms leveled against earlier methods.