Demonstration of oestrogen and progesterone receptors in freeze-dried, paraffin-embedded sections of breast cancer

Comparison of different antibodies for detection of progesterone receptor in breast cancer

Monoclonal antibodies directed against human estrogen receptor (ER) and progesterone receptor (PR) have been used extensively for biochemical and immunohistochemical detection of receptors independent of hormone-binding assays. These antibodies have been valuable both for experimental work and for detection of receptors in clinical breast cancer specimens. The purpose of this study was to characterize the sensitivity and specificity of different antibodies for detection of PR by immunohistochemistry (IHC) of formalin-fixed paraffin breast carcinoma sections. The panel of twelve antibodies included two new ones (PgR636 and PgR1294) produced prospectively to be resistant to formalin fixation and paraffin embedding. Fifty-nine breast carcinomas, having known PR levels by biochemical ligand-binding assay, were used to prepare multitumor paraffin-embedded tissue blocks for characterization of the PR antibodies. Of all the antibodies tested, both PgR636 and PgR1294 stained the highest percentage of breast carcinomas known to be positive by the biochemical assay (95-98%) and they exhibited the highest concordance with the biochemical assay (88-90%). The PgR636 and PgR1294 antibodies, along with one other, PR 88, also gave the highest intensity of nuclear staining, while PgR636 and PgR1294 stained the highest mean percentage of tumor cell nuclei. Antigen retrieval was not necessary for PR immunostaining by PgR636 and PgR1294 in most tumors and other tissues examined, but did slightly increase the staining intensity. The majority of the other antibodies tested were highly dependent on antigen retrieval; only PR 88 and KD 68 antibodies approached the performance of PgR636 and PgR1294 without antigen retrieval. These results indicate that PgR636 and PgR1294 are optimal antibodies for IHC detection of PR in routine paraffin tissue blocks.

Progesterone receptors in routinely paraffin-embedded primary breast carcinomas and lymph node metastases

Described here is an immunohistochemical technique using the commercially available monoclonal progesterone receptor (PR) antibody KD 68 in routinely fixed and paraffin-embedded breast carcinomas and lymph node metastases. The authors' technique is compared with several incubation variations. The method applying the primary antibody in a dilution of 1:10 overnight followed by a biotinylated second antibody showed the best results when Triton X-100 was added to the buffer. Using this method, comparison with the results on frozen sections of 34 breast carcinomas yielded a significant concordance of 94%. Correlation between the results on paraffin sections and those obtained by the standard dextran-coated charcoal cytosol assay was 80%. The value of the method for predicting endocrine therapy response was shown in 20 patients. Thus the reliability of the method has been demonstrated and was applied on 151 lymph node metastases and the corresponding primary breast carcinomas from 50 patients. Generally PR content in the metastases was lower than in the primary tumors (p < 0.001). This finding indicates that evaluation of PR in lymph node metastases should be included in the decision for endocrine therapy of breast cancer.

Freeze-drying of bone tissue: immunocytochemistry and enzyme histochemistry on paraffin embedded and low-temperature resin embedded specimens

A simple protocol of tissue preparation was sought, which would enable marker enzymes of bone cells and extracellular matrix antigens to be localized in the same tissue section with high optical resolution. For this purpose, snap-frozen samples of rat fetal skeletal tissues were dried in a FDU 010 freeze-drying unit (Balzers) for 8-12 h at -50 to -40 degrees C and 0.02 bar. Freeze-dried tissues were either vacuum-infiltrated at 45 degrees C and embedded undemineralized in Paraplast, or vacuum-infiltrated overnight at 4 degrees C and embedded undemineralized in glycol methacrylate. These procedures enabled enzyme cytochemistry for alkaline phosphatase and tartrate-resistant acid phosphatase, and immunocytochemical staining for collagen types I, III, and laminin to be performed on the same sections. No pretreatment of the sections was necessary to reveal collagen antigenicity. This study reveals the possibility of complementing immunocytochemical studies of extracellular matrix with enzyme cytochemistry and, above all, with the excellent tissue preservation and high resolution afforded by plastic embedding.