Immunohistochemical localisation of keratin in human lung tumours

Differential diagnosis between undifferentiated tumor and thymoma by electron microscopy and immunohistochemical labelling

This study of a particular case of tumor posed and resolved problems of differential diagnosis between an undifferentiated tumor and a thymoma by using electron microscopy in association with immunocytochemical methods. The first step was the distinction between an epithelial and a mesenchymal tumor, which was done by electron microscopy and immunofluorescence observation with anti-keratin antibody. The second step, a new approach to this problem, was the distinction between an epithelial tumor of thymic origin and another tumor located in the mediastinal lodge. A clear distinction was made by observation in immunofluorescence using anti-thymulin monoclonal antibody. This double approach permits differential diagnosis, excludes neoplasms of germ-cell origin, malignant lymphomas and leukemias, as well as mesenchymal tumors, and affirms the thymic origin of the tumor observed. A second type of cell observed in this tumor with a peculiar aspect, different from all types of epithelial cells observed in normal thymus, is discussed.

Adenocarcinoma of the lung. Immunohistochemical findings (keratin/CEA)

The reaction patterns in 80 adenocarcinomas of the lung were examined with PAP-method using a monoclonal antibody against keratin and one against carcinoembryonic antigen (CEA) and a polyclonal antiserum against CEA. Almost all tumors showed a positive reaction to the antibodies which, however, varied quantitatively. Even though a reliable correlation of positive immunohistochemical reaction with the different light microscopical types was not possible according to WHO subtypes and degrees of differentiation, specific localization of the reaction within the tumor cells was seen with increasing differentiation. There was no correlation between the immunohistochemical reactions and 14 clinically measured plasma CEA levels. The plasma CEA level not only depends on CEA production by the tumor but also on other factors.

Immunohistological staining of reactive mesothelium, mesothelioma, and lung carcinoma with a panel of monoclonal antibodies

A panel of seven monoclonal antiepithelial antibodies of different specificities, including anticytokeratin, human milk fat globule membrane, C, and carcinoembryonic antigen (CEA) were used with the alkaline phosphatase-antialkaline phosphatase (APAAP) immunostaining technique to determine their value in the differentiation between benign and malignant mesothelial cells and lung carcinoma in histological preparations. The anticytokeratin antibody reacted strongly with all cases of reactive mesothelium, mesothelioma, and lung carcinoma. Antibodies to human milk fat globule membrane and the Ca antigen stained mesothelioma and carcinoma and 43% of cases of reactive mesothelium. Staining for carcinoembryonic antigen was not detected in reactive mesothelium or mesothelioma, but was present in most of the lung carcinomas. CEA seemed to be the single most useful marker in distinguishing carcinoma from mesothelioma in that a positive reaction for CEA would indicate carcinoma rather than mesothelioma.

Large cell carcinoma of the lung. Ultrastructural and immunohistochemical features

Forty one cases of large cell anaplastic carcinoma of the lung (LCACL) were investigated by electron microscopy and immunoperoxidase studies for cytokeratin, enolase, and carcinoembryonic antigen. The results indicated that these neoplasias, grouped as an unique entity by ordinary histopathologic findings, may be further divided into five groups as follows: squamous, adenomatous, adenosquamous, neuroendocrine, and undifferentiated. The authors suggest that this subclassification may be useful in treatment orientation and in the prognostic evaluation of these neoplasias.

Peritoneal cystic mesothelioma: an electron microscopic and immunohistochemical study of two male patients

The clinical, pathological, and ultrastructural features of two cases of peritoneal cystic mesothelioma occurring in men were studied. The results of immunohistochemical staining for CAM 5.2, epithelial membrane antigen, carcinoembryonic antigen, and Factor VIII related antigen are reported for the first time and compared with the staining results of two peritoneal cystic lymphangiomas. Although resembling cystic lymphangioma by light microscopy, cystic mesothelioma may have a greater tendency for local recurrence. Staining for CAM 5.2 or epithelial membrane antigen may facilitate the differentiation of these two entities.

Human lung tumours: a correlation of antigenic profile with histological type

Fifty-four human lung tumours have been immunostained with a large panel of monoclonal antibodies including reagents against cytokeratins, prekeratins, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA) and neural antigens. These results have been compared with the histological types of tumour using the current WHO classification scheme. The most striking finding of this study was the considerable overlap of antigenic profile between different histological types of tumour. This suggests that there may be a greater underlying similarity between different histological categories of lung tumour than has hitherto been assumed. Secondly it was evident that immunostaining highlighted areas of different morphology within many tumours emphasizing the heterogeneous differentiation patterns seen in lung cancers. The present study supports the viewpoint that lung tumours arise from a common stem cell and that these neoplasms represent a single tumour with a tendency to differentiate along one or more pathways.

Differential expression of intermediate filament proteins distinguishes classic from variant small-cell lung cancer cell lines

The expression of intermediate filament proteins in classic and variant-type small-cell lung carcinoma (SCLC) cell lines was studied using immunocytochemical techniques, two-dimensional gel electrophoresis and immunoblotting assays. Classic SCLC cell lines contain cytokeratin proteins but no neurofilaments. In contrast, variant cell lines do not contain detectable amounts of cytokeratins but partly express neurofilaments and vimentin. These results explain apparent discrepancies on the intermediate filament content of SCLC described in the recent literature. The application of antibodies to fresh biopsy specimens of SCLC may in the future allow the identification of the variant type of cells in clinical SCLC specimens and may have a major impact on therapeutic strategy and prognosis in these patients.

Resistance to alkylating agents and tumour differentiation in xenografts of small cell lung cancer

Small cell bronchial carcinoma (SCC) xenografts with differing sensitivity to cyclophosphamide (CY) were investigated using a variety of techniques. Two xenografts (HX78 and HX88) were relatively sensitive to CY, one xenograft (HX72) was inherently resistant to CY and a fourth xenograft (HX78Cy) was a CY induced resistant subline of HX78 and was unstable when maintained without CY exposure. Conventional light microscopy, cytology and electron microscopy examination of the xenografts revealed appearances consistent with SCC. An antikeratin antibody demonstrated the presence of keratin in the inherent and the induced resistant xenografts (and in the unstable revertant) but not in the two sensitive xenografts; the presence of keratin suggested squamous differentiation. Monolayer culture morphology of the sensitive HX78 and the unstable revertant was anchorage independent with the cells forming floating aggregates; the induced resistant subline of this xenograft (HX78Cy) showed, by contrast, flattened, angular adherent cells. Beta HCG production was detected in the monolayer culture supernatant of sensitive HX78 cells; the level of production of beta HCG was increased in the induced resistant HX78Cy cells. Karyotype and flow cytometry studies were also performed. The morphological responses of small cell lung cancer to treatment are discussed.

Distinction of mesothelioma from adenocarcinoma. An immunohistochemical approach

The authors investigated the expression of keratin, carcinoembryonic antigen (CEA), and an epithelial marker derived from milk fat globule membranes in 12 mesotheliomas and 100 diverse adenocarcinomas with immunohistochemical methods. The authors employed a monoclonal antibody to keratin designated as AE1, as well as the following commercially available antisera: rabbit anti-whole human keratin, rabbit anti-CEA, and a monoclonal antibody to an epithelial factor designated as MFG-2. Expression of keratin was found in all the mesotheliomas and adenocarcinomas with antibody AE1 as well as with the rabbit antiserum; CEA was detectable in 65% of the adenocarcinomas but two mesotheliomas also reacted weakly. With antibody MFG-2, positive results were obtained in 85% of the adenocarcinomas and in none of the mesotheliomas. All of 64 (100%) breast-, lung- and ovary-derived adenocarcinomas immunostained positively with antibody MFG-2. This is of particular significance because pulmonary and ovarian adenocarcinoma frequently may be indistinguishable clinically and histologically from epithelial mesothelioma. The authors conclude that antikeratin antibodies are not useful in the distinction of adenocarcinoma from mesothelioma. Because of its greater sensitivity and specificity, MFG-2 is superior to CEA in this differential diagnosis.

Distribution of keratin proteins in neoplastic and tumorlike lesions of squamous epithelium. An immunohistochemical study

Seventy-six cases of tumorlike and neoplastic lesions from epidermis and oral epithelium were analyzed by a histochemical technique for the demonstration of keratin. Formalin-fixed paraffin sections were reacted with rabbit antihuman keratin antiserum (dilution of 1:40). The types of distribution of keratin in cells of lesions were classified into five categories: (1) regional, as found in normal squamous epithelia and benign hyperkeratinized lesions, and papilloma, and keratinized squamous cell carcinoma; (2) total, as seen in intensely keratinized lesions, such as verruca vulgaris and highly keratinized squamous cell carcinoma; (3) negative, as displayed by basal cell carcinoma; (4) scattered, as in the most poorly differentiated squamous cell carcinomas; and (5) mixed cellular, as found in both poorly and moderately differentiated squamous cell carcinomas.

Immunohistological study of malignant diffuse mesotheliomas of the pleura

Paraffin sections from fifteen cases of malignant diffuse mesothelioma of the pleura and five cases of bronchial adenocarcinoma infiltrating the pleura were examined with an antiserum specific for factor VIII related antigen and with antisera against various epithelial markers: keratin, carcinoembryonic antigen (CEA), fat globule membrane antigen and secretory component. In all adenocarcinomas all the epithelial markers were present whereas the factor VIII related antigen was absent. The distribution of the fat globule membrane antigens, keratin, secretory component and factor VIII related antigen varied from one mesothelioma to another. The mesotheliomas were generally negative for CEA. The three mesotheliomas which were positive for CEA were also positive for alcian blue after hyaluronidase treatment. Amongst the markers used, CEA seems the most useful for the differential diagnosis between carcinoma and mesothelioma. However, the simultaneous detection of several markers allows the characterization of various phenotypes. Some of them are close to the phenotypes of true adenocarcinoma. A relation between a given phenotype and the biological behaviour of the tumour has still to be demonstrated.

Bronchial carcinoid cells contain neural-type intermediate filaments

Monospecific antibodies and indirect immunofluorescent microscopic examination, combined with immunochemical analysis, were used to examine intermediate filaments in four cases of bronchial carcinoid tumors. The results show that carcinoid cells express intermediate filaments of neural type (neurofilaments) but are negative for intermediate filaments of mesenchymal type (vimentin), epithelial type (keratin), muscle type (desmin), and glial type (glial fibrillary acidic protein). Since the expression of intermediate filaments shows a high degree of tissue specificity, the results suggest either derivation of bronchial carcinoid cells from maternal cells displaying neural characteristics or from cells with the capacity to acquire neural properties on neoplastic growth. It is also suggested that antineurofilament antibodies can be used as a useful aid in differential diagnosis of bronchial carcinoids from other pulmonary tumors.

Immunocytochemical demonstration of intermediate filaments in a granular cell ameloblastoma

The nature and location of intermediate filament proteins (IFP) may provide new insights into the origin and differentiation of neoplastic cells. An immunofluorescent study of these IFP in a case of a granular cell ameloblastoma revealed that all tumor cells contained the IFP keratin. Some granular cells, however, also contained the IFP vimentin, which is considered specific for mesenchymal tissues only. The implications of these observations are discussed. Study with monoclonal antibodies indicated the origin of the ameloblastoma from non-keratinized squamous epithelium. A comparison of the anti-keratin immunofluorescence pattern of the ameloblast-like cells in the present tumor with ameloblasts in the tooth germ revealed no similarities, indicating that despite some resemblance of the peripheral columnar cells to ameloblasts, these cells differ in other aspects.

Neuroendocrine carcinoma of skin with simultaneous cytokeratin expression

An unusual tumor of the skin was removed from the thigh of a 52-year-old white male. By light microscopy, the tumor was composed of intermediate and small cells in sheets and clusters. Ultrastructural study of the tumor cells showed numerous dense core granules and dendritic cell processes as well as intermediate filaments and cell junctions frequently within the same cells. Most of the tumor cells were stained intensely by antibodies to neurone-specific enolase (NSE), a marker of cells of the central and peripheral nervous system. The neuropeptides met-enkephalin and vasoactive intestinal peptide (VIP) were also found in tumor cells. Immunohistochemistry furthermore demonstrated cytokeratin. Both the ultrastructural appearance and keratin content of this tumor set it apart from conventional Merkel cell (or trabecular) carcinoma of the skin in a manner analogous to bipartite (i.e., epidermoid and small cell) carcinoma of lung. The production of neuropeptides simultaneously with the production of keratin establishes this as a bipartite skin tumor (i.e., ectodermal and neuroectodermal phenotype). We suggest that at least some primary neuroendocrine tumors of the skin arise from multipotential ectodermal cells not of neural crest origin, as has been proposed for small cell carcinoma of lung.

Cytokeratins in normal lung and lung carcinomas. I. Adenocarcinomas, squamous cell carcinomas and cultured cell lines

The various epithelial cells of the lower respiratory tract and the carcinomas derived from them differ markedly in their differentiation characteristics. Using immunofluorescence microscopy and two-dimensional gel electrophoresis of cytoskeletal proteins from microdissected tissues we have considered whether cytokeratin polypeptides can serve as markers of cell differentiation in epithelia from various parts of the human and bovine lower respiratory tract. In addition , we have compared these protein patterns with those found in the two commonest types of human lung carcinoma and in several cultured lung carcinoma cell lines. By immunofluorescence microscopy, broad spectrum antibodies to cytokeratins stain all epithelial cells of the respiratory tract, including basal, ciliated, goblet, and alveolar cells as well as all tumor cells of adenocarcinomas and squamous cell carcinomas. However, in contrast, selective cytokeratin antibodies reveal cell type-related differences. Basal cells of the bronchial epithelium react with antibodies raised against a specific epidermal keratin polypeptide but not with antibodies derived from cytokeratins characteristic of simple epithelia. When examined by two-dimensional gel electrophoresis, the alveolar cells of human lung show cytokeratin polypeptides typical of simple epithelia (nos. 7, 8, 18 and 19) whereas the bronchial epithelium expresses, in addition, basic cytokeratins (no. 5, small amounts of no. 6) as well as the acidic polypeptides nos. 15 and 17. Bovine alveolar cells also differ from cells of the tracheal epithelium by the absence of a basic cytokeratin polypeptide. All adenocarcinomas of the lung reveal a "simple-epithelium-type" cytokeratin pattern (nos. 7, 8, 18 and 19). In contrast, squamous cell carcinomas of the lung contain an unusual complexity of cytokeratins. We have consistently found polypeptides nos. 5, 6, 8, 13, 17, 18 and 19 and, in some cases, variable amounts of cytokeratins nos. 4, 14 and 15. Several established cell lines derived from human lung carcinomas (SK-LU-1, Calu -1, SK-MES-1 and A-549) show a uniform pattern of cytokeratin polypeptides (nos. 7, 8, 18 and 19), similar to that found in adenocarcinomas. In addition, vimentin filaments are produced in all the cell lines examined, except for SK-LU-1.(ABSTRACT TRUNCATED AT 400 WORDS)

Antibodies to intermediate filament proteins in the diagnosis and classification of human tumors

Immunohistochemistry of intermediate filaments (IF) is a new and important way to evaluate the epithelial, mesenchymal, muscular, glial, or neural differentiation in tumors. This is based on the stable cell-type-specific expression of IF proteins in normal and neoplastic tissues. Immunohistochemical studies with antibodies to intermediate filaments have also given new perspectives in the histogenesis and biologic nature of many tumors. This article reviews both the recent findings and the authors' experience in the use of intermediate filament antibodies in tumor diagnosis and classification.

Immunohistochemical localisation of keratin in small cell carcinoma of the lung: correlation with response to combination chemotherapy

Immunohistochemical localisation of keratin was assessed on 45 diagnostic specimens of small cell carcinoma of the lung in patients who subsequently received combination chemotherapy. Nine out of 45 (20%) contained keratin immunoreactive cells. Six of these achieved a complete response to treatment compared to 12 of the tumours which did not show positive staining for keratin. For 2 patients the tumours were shown to contain nests of keratin immunoreactive cells. Both of these are alive and free of disease more than 5 yr after the initial diagnosis. The results indicate that the presence of keratin immunoreactive cells may not directly equate with squamous differentiation and therefore not constitute an adverse prognostic factor in terms of response to chemotherapy.

An assessment of the value of epithelial membrane antigen and other epithelial markers in solving diagnostic problems in tumour histopathology

Using standard immunohistological techniques on formalin-fixed paraffin-embedded sections, we have evaluated the role of epithelial membrane antigen in the histopathological diagnosis of tumours. Of the 70 samples examined, 22 were taken for staging purposes from patients known to have carcinoma and, in half these cases, malignant cells were seen which could not be identified with confidence by conventional means. Forty-eight tumours were stained in order to determine their histogenesis. Twenty-two of these were positive and 20 subsequently proved to be epithelial on follow-up studies, including six in which a diagnosis of non-epithelial malignancy had been made on conventional preparations. The distinction of anaplastic carcinoma from malignant lymphoma and of spindle-cell carcinoma from sarcoma were the most useful applications. One of the positive tumours was of germ cell origin and in one the histogenesis is still not clear. Comparison with carcinoembryonic antigen and pre-keratin showed that epithelial membrane antigen was the most sensitive marker of epithelial differentiation in formalin-fixed tissue. A combination of all three reagents, though, increases diagnostic accuracy and allows tentative suggestions to be made about the possible site of origin of a metastatic carcinoma.

Antibodies to intermediate filament proteins in the immunohistochemical identification of human tumours: an overview

Intermediate-sized filament proteins (IFP) are tissue specific in that antibodies to keratin, vimentin, desmin, glial fibrillary acidic protein (GFAP) and the neurofilament proteins can distinguish between cells of epithelial and mesenchymal origin as well as of myogenic and neural origin respectively. Malignant cells retain their tissue-specific IFP, which makes it possible to use these antibodies in tumour diagnosis. Carcinomas are exclusively detected by antibodies to keratin. Monoclonal antibodies to keratin have allowed the differentiation between subgroups of epithelial tumours until now between adenocarcinomas and squamous cell carcinomas. Lymphomas, melanomas and several soft tissue tumours are distinctly recognized by antibodies to vimentin. On the other hand, rhabdomyosarcomas and leiomyosarcomas are positive for desmin, while astrocytomas give a strong reaction with GFAP antibodies. Thus, antibodies to IFP are useful tools for differential diagnosis in surgical pathology.

Epithelial markers in the diagnosis of nasopharyngeal carcinoma: an immunocytochemical study

Immunocytochemical stains for three epithelial cell markers--keratin, epithelial membrane antigen (EMA) and carcinoembryonic antigen (CEA)--have been examined on paraffin-embedded material from 14 patients with nasopharyngeal carcinoma (NPC). Tumour cells staining positively for keratin were found in all cases and for EMA in eight; two tumours contained CEA-positive cells. Seven cases of Hodgkin's disease and 24 non-Hodgkin's lymphomas were uniformly negative. Keratin is the most reliable epithelial marker for identifying NPC and excluding lymphoma. The regular finding of stainable keratin in non-keratinising and anaplastic NPC supports the view that NPC is a homogeneous group exhibiting variable degrees of squamous differentiation.