Olof Moesker

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

SummaryIntermediate-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.

Tissue distribution of keratin 7 as monitored by a monoclonal antibody

Monoclonal antibody (RCK 105) directed against keratin 7 was obtained after immunization of BALB/c mice with cytoskeletal preparations from T24 cells and characterized by one- (1D) and two-dimensional (2D) immunoblotting. In cultured epithelial cells, known from gel electrophoretic studies to contain keratin 7, this antibody gives a typical keratin intermediate filament staining pattern, comparable to that obtained with polyclonal rabbit antisera to skin keratins or with other monoclonal antibodies, recognizing for example keratins 5 and 8 or keratin 18. Using RCK 105, the distribution of keratin 7 throughout human epithelial tissues was examined and correlated with expression patterns of other keratins. Keratin 7 was found to occur in the columnar and glandular epithelium of the lung, cervix, breast, in bile ducts, collecting ducts in the kidney and in mesothelium, but to be absent from gastrointestinal epithelium, hepatocytes, proximal and distal tubules of the kidney and myoepithelium. Nor could it be detected in the stratified epithelia of the skin, tongue, esophagus, or cervix but strongly stained all cell layers of the urinary bladder transitional epithelium. When applied to carcinomas derived from these different tissue types it became obvious that an antibody to keratin 7 may allow an immunohistochemical distinction between certain types of adenocarcinomas.

Expression of cytokeratins in early neoplastic epithelial lesions of the uterine cervix

SummaryPolyclonal and monoclonal antibodies to cytokeratin polypeptides were used to study the expression of these intermediate filament proteins in normal, squamous metaplastic, and neoplastic epithelium of the uterine cervix, in order to investigate the morphogenesis of early epithelial changes preceding cervical squamous cell carcinoma. A polyclonal keratin antiserum showed a positive reaction in all different epithelial cell types of the uterine cervix. A positive reaction was also found in subcolumnar reserve cell hyperplasia, in squamous metaplastic and dysplastic cells, and in (squamous) carcinoma in situ. A monoclonal antibody specific for columnar epithelium (RGE 53) gave a positive reaction in endocervical columnar cells and in some immature metaplastic cells but was negative in subcolumnar reserve cells, squamous (metaplastic} cells, dysplastic cells, and most cases of carcinoma in situ. Another monoclonal cytokeratin antibody (RKSE 60) pointed to early keratinization in light microscopically nonkeratinizing squamous (metaplastic) and dysplastic epithelium. A possible overlap in staining patterns of RGE 53 and RKSE 60 was seen in some cases of immature metaplasia. Morphologic changes occurring in the transformation zone upon dedifferentiation are accompanied by alterations in cytokeratin expression. Similarities in cytokeratin expression were found between dysplasia and carcinoma in situ on one hand and subcolumnar reserve cell hyperplasia and squamous metaplasia on the other. This study favors an epithelial origin and a squamoid nature of subcolumnar reserve cells.

Antibodies to cytokeratin and vimentin in testicular tumour diagnosis

Thirteen primary and metastatic testicular germ cell tumours, including classical and anaplastic seminomas, and non-seminomatous testicular tumours were examined for their intermediate filament protein (IFP) types. The seminomas were shown to react with a monoclonal and a polyclonal antibody to bovine lens vimentin, while non-seminomatous germ cell tumours were strongly positive for a polyclonal and a monoclonal antibody to cytokeratin. In one case of seminoma with elevated serum levels ofβHCG andαFP, cytokeratin positive tumour cells were found. In the case of teratocarcinoma, several components of the tumour could be distinguished using a combination of antisera in double-label immunofluorescence microscopy. The glandular component of this tumour was positive with the polyclonal antikeratin, but also with the monoclonal cytokeratin antibody specific for glandular epithelia (RGE 53). However, the squamous component was negative with this latter antibody. Strikingly, the spindle cell component showed focal positivity for vimentin, with coexpression of cytokeratin and vimentin in some cells. Our data show that antibodies to cytokeratin and vimentin can be helpful in the diagnosis of testicular germ cell tumours, especially in the differentiation between seminomas and non-seminomatous tumours.

Differential diagnosis of human carcinomas, sarcomas and their metastases using antibodies to intermediate-sized filaments☆

Intermediate filaments (IF) are tissue-specific in so far that epithelial, mesenchymal, muscle and neural tissue types can be distinguished by the use of specific antibodies to keratin, vimentin, desmin and neurofilaments or glial filaments respectively. We have examined the possibility of using these sera in the differential diagnosis of human malignant tumors. Using antisera to human skin keratin and bovine lens vimentin we could differentiate between carcinomas (keratin +) and sarcomas (vimentin +). Furthermore, we could show that when cells become malignant and metastasize they retain their original IF and do not develop additional IF systems. We conclude that antibodies to IF proteins are powerful tools in the hands of a pathologist as an additional method to improve identification of tumors and their metastases.

Interphase cytogenetics on paraffin sections of malignant pleural mesothelioma : a comparison to conventional karyotyping and flow cytometric studies

We performed in situ hybridization (ISH) studies of malignant pleural mesotheliomas to detect numerical aberrations of chromosomes 1 and 7 in interphase nuclei of paraffin sections of 13 cases that had been analyzed previously by conventional karyotyping and flow cytometry. The hybridizations were performed with the biotin-labeled probes recognizing repetitive DNA sequences in the (peri)centromeric regions of chromosomes 1 (1q12) and 7(7cen). Application of histologic sections allowed us to analyze the tumor cells only. Comparison of the karyotype and ISH studies showed that the same chromosome copy numbers were detectable by both methods in 13 (chromosome 1) and in 12 (chromosome 7) cases evaluable by ISH. DNA indexes determined in the paraffin-embedded tumor material corresponded with the ISH findings. As compared with karyotype analysis, ISH showed a larger heterogeneity in chromosome copy numbers. The results can be divided into three groups: 1) Monosomy or disomy of chromosomes 1 and 7 was detected by both methods in two cases; 2) in four cases, disomy of both chromosome 1 and 7 was observed in most of the cells by ISH analysis, and karyotype analysis had shown clear polyploidization in three of these cases; 3) in seven cases, supernumerary copies of chromosomes 1 and/or 7 were present in an evident fraction (27-80%) of the cells analyzed by ISH, and karyotype analysis confirmed the aberrant copy numbers in five of these cases. On the other hand, ISH showed copy numbers not detected by karyotype analysis in six of the seven cases. Thus, by combining karyotype and interphase cytogenetic studies, complementary information about chromosomal aberrations in mesothelioma is obtained.

Application of antibodies to intermediate filament proteins in simple and complex tumors of the female genital tract

Polyclonal antibodies to cytokeratins, vimentin, and desmin and monoclonal antibodies to vimentin and to individual cytokeratin polypeptides, specific for glandular epithelia (RGE 53) or kertinizing stratified squamous epithelia (RKSE 60), have been applied in gynecological tumors with simple or complex composition. In general, tumors with simple composition showed reaction patterns fitting their known epithelial or mesenchymal nature, i.e., cytokeratin positivity in epithelial tumors only, vimentin positivity in mesenchymal tumors, and expression of desmin and vimentin in muscle cell tumors. Rather frequently, coexpression of cytokeratins and vimentin was noted in endometrial adenocarcinomas. Tumors with complex composition, such as müllerian mesodermal mixed tumors (MMMTs), that may pose considerable problems in conventional histopathology revealed various reaction patterns, with either expression of only cytokeratins or coexpression of cytokeratins and vimentin in carcinomatous areas and expression of only vimentin in sarcomatous areas. However, in addition, some MMMTs contained cells that were also positive for desmin. Intermediate filament protein immunohistochemistry appeared to be helpful in establishing a diagnosis of MMMT and in characterizing the different tumor components, which may prove to be useful in the evaluation of gynecological treatment protocols.

The use of antibodies to intermediate filament proteins in the differential diagnosis of lymphoma versus metastatic carcinoma

SummaryForty-nine cases encompassing 16 different types of malignant lymphoma were examined for their intermediate filament protein (IFP) type by indirect immunofluorescence microscopy of cryostat sections. In all cases, vimentin was shown to be the only IFP type detectable in these tumours. Lymphomas are negative for keratin and desmin, which are characteristic for benign and malignant epithelial or muscular tissues respectively. In addition, eighteen cases are described in which antibodies to intermediate filament proteins were used successfully to distinguish between lymphoma and metastatic carcinoma where differential diagnosis was difficult or impossible on the basis of routine histology.

Immunohistochemical identification of Langerhans cells in normal epithelium and in epithelial lesions of the uterine cervix

Using the double label indirect immunofluorescence technique we have studied vimentin-positive cells present in normal ecto- and endocervical epithelium, subcolumnar reserve cell hyperplasia, and squamous metaplastic and dysplastic epithelium of the uterine cervix. Monoclonal antibodies to Ia- and T6-antigens were applied in the examination of the expression of these membrane markers by such cells. Our studies reveal the presence of a relatively large number of vimentin-positive and T6-positive (Langerhans) cells in normal ectocervical stratified squamous epithelium, a small number in endocervical columnar epithelium, and a larger number in subcolumnar reserve cell hyperplasia and in immature squamous metaplasia. In this respect, mature squamous metaplastic epithelium shows a great resemblance to normal ectocervical stratified squamous epithelium. In contrast with previous reports in the literature we could only demonstrate small numbers of Langerhans cells in cases of dysplasia. The clinicopathological significance of these findings is discussed.

Monoclonal Antibodies to Cytokeratins in the Study of Premalignant Lesions of the Uterine Cervix

Abstract Cytokeratins are intermediate filament proteins that occur specifically in epithelial cells. Using antibodies to these proteins epithelial cells can be detected specifically by immunohistochemical methods. Thus, using a polyclonal rabbit antiserum to keratin in the indirect immunofluorescence technique on frozen tissue sections from normal cervix, ectocervical stratified squamous epithelium, endocervical columnar epithelium and the so-called reserve cells show a positive staining reaction. A monoclonal antibody, raised against cytokeratin 18 specifically recognizes columnar epithelial cells. This type of cytokeratin is not detectable in reserve cells, endocervical nature squamous metaplastic and dysplastic epithelial cells. A second monoclonal antibody specifically stains keratinizing cells in stratified squamous, squamous metaplastic and dysplastic epithelium. These data indicate that alterations in cytokeratin expression occur in premalignant lesions of the uterine cervix.