MABT1530-25UL Sigma-AldrichAnti-Cytokeratin HMW Antibody, clone 34betaE12

There is no well-established positive immunomarker for urothelial carcinoma. We evaluated the diagnostic utility of high molecular weight cytokeratin (HMWCK) antibody clone 34betaE12 in differentiating high-grade invasive urothelial carcinoma from prostate cancer.Formalin-fixed paraffin-embedded sections from 28 cases of high-grade invasive urothelial carcinoma (20 not otherwise specified (UC-NOS), eight with glandular differentiation) and 20 cases of poorly differentiated prostate carcinoma were immunostained with a monoclonal antibody to carcinoembryonic antigen (CEA), clone 85A12 and with HMWCK antibody clone 34betaE12 after microwave pretreatment or protease 24 predigestion. All cases of UC-NOS expressed HMWCK on 34betaE12 immunostaining after microwaving or enzyme predigestion. Immunoreactivity was intense and diffuse in all the cases after microwave pretreatment, whilst with enzyme predigestion immunoreactivity was sometimes patchy with <50% tumour cells positive in 20% of cases. In comparison with 34betaE12, 85A12 was insensitive with 15% of UC-NOS cases totally CEA-negative and <50% tumour cell immunoreactivity in 60% of cases. Rare positive cells were present in two (10%) cases of prostate cancer with monoclonal anti-CEA and 34betaE12 on microwaved sections, but all the cases were HMWCK-negative using 34betaE12 on sections pretreated by enzyme digestion.HMWCK antibody clone 34betaE12, particularly when used with microwave heat retrieval, is a very sensitive positive marker for high-grade invasive urothelial carcinoma.

We included in our study nine normal human thymuses and sixteen thymomas (1 type A, 2 type AB, 3 type B1, 3 type B2, 5 type B3 and 2 type C). The 25 patients were between 7 days and 75 years old, and were submitted to open surgery for correction of congenital heart defects or for mediastinal tumor mass. Biopsies were formalin fixed for 24 hours and then embedded in paraffin using routine procedure. Five micrometers step sections were mounted on silanized slides. Slides from each case were stained with haematoxylin and eosin method for morphological diagnosis. Additional sections were immunostained using monoclonal antibodies against high molecular weight cytokeratin clone 34beta E12. We found a very strong positive reaction for this type of cytokeratin in thymomas type B2, B3 and inconstant in type C comparative with normal thymus. Also, the number and distribution of positive epithelial cells in normal thymus versus thymomas were different. We found positive cells into capsular vessels of thymomas. This could be an invasion marker for apparent encapsulated thymomas. Strong positive reaction in almost all epithelial cells of thymomas types mentioned above was correlated in part with invasion. We concluded that expression of 34beta E12 cytokeratin is a useful marker for thymomas with high grade of malignacy, correlated with vascular and capsular invasion.

Monoclonal antibodies generated against different human intermediate filament (IF) proteins were assayed on fixed, embedded tissue by the biotin-avidin-immunoperoxidase method for evaluation of the tissue specificity of these antibodies. An antibody (43 beta E8) made to fibroblast IF protein stains mesenchymal tissue such as endothelium, histiocytes, stromal fibroblasts, and Schwann cells but does not stain epithelium, skeletal muscle, lymphocytes, or neurons. Three different anti-cytokeratin antibodies decorate epithelium in three unique patterns. One (35 beta H11) stains all nonsquamous epithelium but fails to recognize squamous epithelium. Antibody 34 beta E12 stains the full thickness of squamous epithelium and ductular epithelium but does not react with hepatocytes, pancreatic acinar cells, proximal renal tubules, or endometrial glands. Antibody 34 beta B4 stains only the suprabasal portion of squamous epithelium. None of these three anti-cytokeratin antibodies reacts with nerve or mesenchymal tissue. Two anti-neurofilament antibodies recognize only neurons, failing to react with epithelial or mesenchymal tissue. We conclude that these anti-intermediate filament antibodies can be used as tissue-specific markers. Neoplasms retain the same intermediate filament patterns as the normal parental tissue; therefore, these antibodies can be used as diagnostic aids in surgical pathology.