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

The Expression Pattern of Epidermal Differentiation Marker Keratin 10 in the Normal Human Breast and Breast Cancer Cells

Cells of the human breast gland express an array of keratins, of which some are used for characterizing both normal and neoplastic breast tissue. However, the expression pattern of certain keratins has yet to be detailed. Here, the expression of a differentiation marker of epidermal epithelium, keratin 10 (K10), was investigated in the human breast gland. While in normal breast tissue generally less than 1% of luminal epithelial cells expressed K10, in women >30 years of age glandular structures with K10-positive (K10^pos) cells were found at higher frequency than in younger women. K10^pos cells belong to a mature luminal compartment as they were negative for cKIT, positive for Ks20.8, and mostly non-cycling. In breast cancer, around 16% of primary breast carcinomas tested were positive for K10 by immunohistochemistry. Interestingly, K10^pos tumor cells generally exhibit features of differentiation similar to their normal counterparts. Although this suggests that K10 is a marker of tumor differentiation, data based on gene expression analysis imply that high levels of K10 dictate a worse outcome for breast cancer patients. These findings can form the basis of future studies that should unravel which role K10 may play as a marker of breast cancer.

Morphological changes of telocytes in camel efferent ductules in response to seasonal variations during the reproductive cycle

Telocytes (TCs) are a distinct stromal cell type described in many organs. The present study investigated the existence of TCs within the efferent ductules in camel and the changes that occur in their morphology and activity during active and inactive reproductive seasons. TCs in the camel had a cell body and multiple telopodes (TPs), and most TCs had indented nuclei that exhibited prominent intranucleolar chromatin. TCs exhibited seasonal differences which were evaluated by histochemistry, immunohistochemistry (IHC), Transimition electron microscopy (TEM) and scanning electron microscopy (SEM). The presence of TCs in camel efferent ductules has been confirmed by CD34 positive immunostaing. In addition to the expression of the vascular endothelial growth factor (VEGF) which was stronger in the summer season. TCs exhibited stronger immunoreactivity for progesterone and oestrogen alpha receptors (ESR1) in the spring than in the summer. In addition, TCs showed strong positive immunostaining for both vimentin and androgen receptor (AR). Several ultrastructural changes were observed in TCs during the two seasons. TPs in the summer season had delicate ramifications whereas, in the spring, TPs displayed fine arborization and became more corrugated. TCs acquired signs of exaggerated secretory activities in the spring; TPs became expanded and packed with secretory vesicles. Thus, we conclude that, hormonal alterations during the reproductive cycle impact the morphology and secretory behavior of TCs.

Canine vascular neoplasia--histologic classification and inmunohistochemical analysis of 221 tumours and tumour-like lesions

A light microscopic evaluation of 221 canine vascular tumours and tumour-like lesions, supplemented by immunohistochemistry (von Willebrand Factor, CD31, vimentin), revealed a high degree of conformity with similar conditions in humans. Four main categories of tumours are reported, i.e. benign types: haemangiomas (n=127) and lymphangioma (n=1); tumour-like lesions: papillary endothelial hyperplasia (n=8) and vascular ectasias (n=2); neoplasms of intermediate malignancy: haemangioendotheliomas (n=27), and the obvious malignant form: angiosarcomas (n=57). Further classification showed that all subtypes had their human counterparts. Papillary endothelial hyperplasia and arteriovenous and venous haemangiomas are described for the first time in dogs. The combination of conventional histopathologic methods and immunohistochemistry was in many cases very useful diagnostically, the latter technique being in some cases indispensable for establishing a definite diagnosis. In general CD31 was the most useful marker for tumours originating from endothelial cells, especially for poorly differentiated haemangiosarcomas.

Expression and distribution of intermediate-filament proteins and laminin during the development of the bovine Müllerian duct

The expression pattern of several intermediate-filament proteins (vimentin, cytokeratin 8, 18 and 19) and the basal lamina component laminin was investigated in the Wolffian and the Müllerian ducts of bovine embryos and fetuses. The material studied comprised sexually undifferentiated stages [crown-rump length (CRL) 0.9 cm/1.0 cm/1.2 cm/1.9 cm/2.5 cm] and female stages (CRL 3.0 cm/4.2 cm/5.1 cm). Laminin could be demonstrated in the basal lamina of the developing Wolffian and Müllerian duct as well as in the stroma surrounding the Müllerian duct. The intermediate-filament protein vimentin was expressed in the mesothelium of the funnel field and in the epithelium of the Müllerian duct in all studied specimens, whereas the epithelial cells of the Wolffian duct only showed vimentin expression from a CRL of 2.2 cm onwards. In the cranial part of the Müllerian ducts only a few cells stained with pan-cytokeratin antibodies, whereas mesothelium and epithelium of the Wolffian duct showed as distinct immunostaining in all investigated stages. Both genital ducts showed no immunostaining with the antibody against cytokeratin 19 at any time of development. We conclude from our immunohistochemical results that the epithelial cells of the Wollfian duct do not contribute cells to the developing Müllerian duct.

Evaluation of 3-nitrotyrosine as a marker for 3-nitropropionic acid-induced oxidative stress in Lewis and Wistar rats and strain-specific whole brain spheroid cultures

The present study investigated whether 3-nitrotyrosine is an early marker for neurodegenerative processes involving oxidative stress. We characterized the 3-nitrotyrosine formation after 3-nitropropionic acid (3-NP) exposure in the whole brain spheroid culture model and in a rat model, using Lewis and Wistar rats. Increased 3-nitrotyrosine concentration in spheroid cultures from Lewis rats was observed at lower dose of and shorter exposure time to 3-NP as compared to alterations in glial fibrillary acidic protein concentration, decrease in glutamine synthetase activity or cell loss. Five days of exposure to 3-NP (5 mM) resulted in decreased staining of GABAergic processes, while neuronal nitric oxide synthase staining was preserved. In addition, staining of EAAC1, anti-2',3'-cyclic nucleotide 3'-phosphohydrolase and ED1 was diminished after treatment of spheroid cultures with 3-nitropropionic acid (5 mM), while isolectin B4 staining was increased. Dithiothreitol and vitamin E inhibited the increased formation of 3-nitrotyrosine. Interestingly, N(G)-nitro-L-arginine methyl ester increased the 3-nitrotyrosine formation. No increased 3-nitrotyrosine concentration was shown after exposure to 3-nitropropionic acid during 5 days in spheroid cultures obtained from Wistar rats. In the striatum of 3-NP-exposed Lewis and Wistar rats, no change in 3-nitrotyrosine concentration was observed, whereas only in Wistar rats the glial fibrillary acidic protein concentration was increased in addition to activation of microglial cells. It is concluded that 3-nitrotyrosine was a more sensitive marker for oxidative stress-induced neurodegeneration than glial fibrillary acidic protein and glutamine synthase in spheroid cell cultures of Lewis rats. Finally, the similarities between the 3-NP spheroid model and the vivo model indicate that the spheroid cultures provide a good alternative for chronic exposure of animals to neurotoxins.

VML 295 (LY-293111), a novel LTB4 antagonist, is not effective in the prevention of relapse in psoriasis

Leukotriene B4 (LTB4) receptor antagonists have been the subject of several studies in the treatment of inflammatory diseases, including psoriasis. A novel oral LTB4 antagonist, VML 295 (LY-293111) has recently been developed and has a pronounced effect on epidermal inflammatory parameters. However, oral treatment of psoriasis for 4 weeks did not result in a decrease in disease severity. The present study was performed in order to investigate whether prolonged treatment with VML 295 up to 8 weeks has a beneficial effect on the overall severity of psoriasis. Moreover, we studied to what extent VML 295 is able to prevent relapse in psoriasis. In the present study, 35 patients with stable chronic plaque psoriasis were included. A representative plaque of at least 16 cm2 was initially treated with clobetasol-17-propionate lotion under hydrocolloid occlusion in all patients. Clearance was achieved within 6 weeks in 31 patients. After clearance, the patients were randomized to treatment and received oral VML 295 capsules 200 mg twice daily or placebo for 8 weeks. Twenty-five patients completed the study. The psoriasis area and severity index (PASI) was assessed before treatment, at clearance, and on days 15, 29, 43 and 5 7 of the treatment period. Biopsies were taken from the treated lesion before treatment, after clearance and at relapse, and cells were analysed by flow cytometry with markers for differentiation (keratin 10), inflammation (vimentin), and proliferation (DNA content). After 8 weeks of treatment, 14 of 15 VML 295-treated patients had relapsed and 11 of 16 placebo-treated patients had relapsed. A total of six patients were withdrawn. The time to relapse and the number of relapsed patients was not significantly different comparing the treatment groups. There was no significant difference in PASI scores between VML 295-treated patients and placebo-treated patients after 8 weeks of treatment. Flow cytometric parameters for differentiation, inflammation and proliferation did not show significant differences between VML 295- and placebo-treated patients. We conclude that oral VML 295 (LY-293111) is not effective in preventing relapse in psoriasis, either clinically or at the cellular level, and that in our group of patients VML 295 had no beneficial effect on overall psoriasis severity. Moreover, we conclude that further development of LTB4 modulating drugs for the treatment of psoriasis is not indicated.

Paraffin immunohistochemistry as an adjunct to hematopathology

In the past two decades, there have been a number of dramatic advances in immunology that have subsequently affected immunohistochemistry. These have had a substantial impact on all phases of laboratory medicine, especially surgical pathology. Many hospital laboratories use immunohistochemical analysis on paraffin-embedded tissue sections as routinely as other special histochemical techniques. Hematopathology, in particular, has become increasingly reliant on the immunohistochemical antibody technique. This method aids in the identification of lineage-associated or lineage-restricted antigens in hematolymphoid neoplasms. The demonstration of kappa or lambda light-chain restriction is a good indicator of monoclonality in B-cell processes, aiding in the distinction between benign reactive hyperplasia and malignant lymphoma. Increasing numbers of antibodies that react to cluster differentiation cell surface antigens have become available for use in paraffin-embedded sections, obviating the need for frozen tissue in many cases. This facilitates the collection, processing, shipping, and storage of tissue specimens for immunohistochemical studies. This report will discuss the basic concepts in the immunohistochemical technique and show its applicability to hematopathology. It will also describe the most relevant antigens/antibodies and how they are used in antibody panels for the diagnosis of benign and malignant hematolymphoid lesions.

The effect of long-term treatment with tacalcitol on the psoriatic epidermis. A flow cytometric analysis

During the last decade, novel analogues of 1alpha,25-dihydroxy vitamin D3 have been developed for the treatment of psoriasis. Recently, the efficacy of short-term treatment with the novel derivative tacalcitol (1alpha,24-dihydroxy vitamin D3) has been documented. However, data on the long-term effect of tacalcitol on psoriatic skin are sparse. In this study, we assessed the cell characteristics of the psoriatic epidermis after treatment with tacalcitol for up to 24 weeks. We investigated how long-term treatment with tacalcitol modulates the percentages of differentiated keratinocytes, inflammation cells and basal keratinocytes, and the percentage of cells in the SG2M phase in the basal cell population. From 11 patients who were treated with tacalcitol for up to 18 months, we obtained single-cell suspensions of a representative psoriatic lesion after 0, 8, 12, 18 and 24 weeks of treatment. A Psoriasis Area and Severity Index was performed at each visit as well. Cell suspensions were stained with markers for inflammation (Vim3B4), differentiation (RKSE60) and proliferation (TO-PRO-3 iodide) and analysed flow cytometrically. Clinically, patients improved significantly after 8 weeks of treatment. This clinical effect was preserved for the rest of the period of treatment with no further significant improvement. Proliferative activity also decreased significantly after 8 weeks of treatment. Proliferation did not show further significant decreases or habituation after 12, 18 and 24 weeks. For inflammation, no statistically reliable trends could be seen. Differentiation improved significantly after 8 weeks of treatment, but decreased again significantly after 12 weeks. In the period from 12 to 24 weeks, no further significant change was observed. We conclude that tacalcitol is an effective antipsoriatic drug. Prolonged treatment with tacalcitol will generally maintain improvement at the level reached after 8 weeks. Owing to the beneficial effect on both clinical state and proliferation, tacalcitol is likely to be an adequate maintenance therapy.

Emergence of an irreversible differentiated subclone from the poorly differentiated ovarian adenocarcinoma cell line AMOC-2 treated with sodium butyrate

OBJECTIVE

To cast light on the capacity of an ovarian adenocarcinoma to undergo irreversible cellular differentiation, we established clonal cell lines from cultured ovarian carcinoma cells treated with sodium butyrate and examined their phenotypic changes.

METHODS

The poorly differentiated ovarian carcinoma cell line AMOC-2 was exposed to 2 mM sodium butyrate for 30 days, and clonal cell lines were established by a dilution plating technique.

RESULTS

Five clonal cell lines were established. One of them had a longer doubling time and lower plating efficiency than the parental clone, also demonstrating stronger expression of vimentin and 56 kD cytokeratin. This clone became columnar with pronounced polarity, formed gland-like structures when cultured in collagen gels, and exhibited no tumorigenicity, in contrast to the parental clone.

CONCLUSION

Sodium butyrate treatment of AMOC-2 cells can cause phenotypic changes reminiscent of maturation in the Müllerian duct, endocervix, and/or endometrium.

The cytoskeletal intermediate filaments of canine retinal pigment epithelial cells in vivo and in vitro

The cytoskeletal intermediate filament characteristics of normal, freshly isolated and subcultured canine retinal pigment epithelial (RPE) cells were studied using immunocytochemistry and immunoblotting techniques. Commercially available primary antibodies recognising a broad range of cytokeratins and vimentin were selected. Cytokeratin reactivity was a constant feature of all canine RPE cells. The main cytokeratins expressed by cultured RPE cells included 8, 18 and 19. This finding is consistent with the published findings of work carried out in other mammalian species including man. Freshly isolated RPE cells stained positively with broad-spectrum antibodies to cytokeratins but generally did not stain with antibodies specific to cytokeratins 18 or 19 and did not stain with antibodies to vimentin, or stained only very weakly. After a short time in culture however, cells demonstrated intense positive staining for vimentin. This study demonstrated that cytokeratin immunoreactivity (in conjunction with vimentin immunoreactivity in vitro) is a useful and consistent marker for canine RPE cells.

Establishment and characterization of a renal cell carcinoma line from a patient with von Hippel-Lindau syndrome

It is not known how the von Hippel-Lindau (VHL) gene and the, as yet unidentified, renal cell carcinoma (RCC) gene(s) interact to result in RCC; nor is it known if mutations in both, or all genes are necessary for this progression. The availability of a RCC cell line from a VHL patient would be useful in studies comparing sporadic RCC with RCC resulting from VHL syndrome; and for determining the relationship or interaction of the RCC gene with the VHL gene to produce a common tumor type. This paper describes the isolation and characterization of a renal cell carcinoma cell line derived from a patient with von Hippel-Lindau disease. The line is epithelial in origin and the genome contains a familial mutation in the VHL gene. Tissue culture studies indicate that this cell line, although immortalized, is not fully transformed. Chromosomal analysis performed on cells derived from disseminated primary tumor cells revealed no detectable chromosomal abnormalities. However, analysis performed on cells at passages 9, 19, 41, and 79 showed both numerical and structural chromosomal changes. The cytogenetic profile of this cell line demonstrated a number of abnormalities known to be associated with RCC from patients with and without VHL syndrome.

Keratin intermediate filament dynamics in cell heterokaryons reveals diverse behaviour of different keratins

To study the dynamics of keratin intermediate filaments, we fused two different types of epithelial cells (PtK2 and BMGE+H) and studied how the keratins from the parental cells recombine and copolymerize to form the heterokaryon cytoskeleton. The behaviour of the keratins during this process was followed by immunofluorescence using specific antibodies. After fusion, the parental cytoskeletons undergo a depolymerization process most apparent in the region adjacent to the fusion area. The depolymerized subunits spread throughout the heterokaryon and copolymerize into a new hybrid cytoskeleton. The complete process is very rapid, occurring in 3–4 hours, thus demonstrating the highly dynamic nature of the keratin cytoskeleton. Although newly synthesised subunits contribute to the formation of the hybrid cytoskeleton, the process takes place with similar kinetics in the absence of protein synthesis, showing the dynamic nature of the keratins from pre-existing cytoskeletons. During this process, specific keratins behave differently. Keratins K8, K18, K5 and K10 are mobilised from the parental cytoskeletons and reassemble rapidly into the hybrid cytoskeleton (3–6 hours), whereas K14 requires a substantially longer period (9–24 hours). Thus, different keratins, even when they form part of the same heterodimeric/tetrameric complexes, as is the case for K5 and K14, exhibit different dynamics. This suggests that individual polypeptides or homopolymeric complexes rather than exclusively heterodimeric/ tetrameric subunits, as is currently thought, can also take part in keratin intermediate filament assembly and dynamics. Biochemical analysis performed in the absence of protein synthesis revealed greater amounts of K5 than of K14 in the soluble pool of BMGE+H cells. Crosslinking and immunoprecipitation experiments indicated an excess of monomeric K5, as well as of K5/K14 heterodimers and K5 homodimers in the soluble pool. These results are in agreement with the different dynamic behaviour of these keratins observed in immunofluorescence. On the contrary, the phosphorylation levels of K5 and K14 are similar in both the soluble pool and the polymerized fraction, suggesting that phosphorylation does not play an important role in the different dynamics displayed by these two proteins. In summary, our results demonstrate that, following fusion, the keratin intermediate filament network reshapes rather rapidly and that keratins are highly dynamic proteins, although this mobility depends on each particular polypeptide.

Characterization of residual tumor cells following radical radiation therapy for prostatic adenocarcinoma; immunohistochemical expression of prostate-specific antigen, prostatic acid phosphatase, and cytokeratin 8

BACKGROUND

Our knowledge about the nature and biological activity of tumor cells residing in the prostate gland after radical radiotherapy (RRT) is limited.

METHODS

In the present study, residual tumor in core biopsies taken from 37 patients after an average of 6.8 years follow-up after radiation, were investigated with immunohistochemistry for the biochemical markers prostate-specific antigen (PSA), prostatic acid phosphatase (PAP), and the epithelial marker, cytokeratin 8 (CK8).

RESULTS

Tumor cells were cytokeratin-positive in 33 of 34 evaluable specimens (97%). PSA and PAP were expressed in the tumor cells in 94% (34/36) and 81% (30/37) of cases, respectively. No significant correlation was observed between PSA/PAP expression and tumor grade after treatment. Endocrine treatment administered in addition to RRT in 12 of the 37 patients did not affect the expression of PSA or PAP. The expression of both biochemical markers was reduced after radiotherapy in 10 of the 12 cases for which pre- and post-treatment specimens were available.

CONCLUSIONS

Tumor cells retain their epithelial characteristics immunohistochemically after radiation, though their morphology sometimes suggests an altered phenotype after treatment. PSA and PAP reactivity was demonstrated in tumor cells nearly 7 years after radiotherapy, which indicates that these cells maintain their biochemical integrity and protein synthesis to a certain extent. Furthermore, endocrine treatment did not abolish PSA or PAP expression in the tumor cells. Whether PSA and PAP immunoexpression provides independent prognostic information needs to be further investigated.

Smoothelin, a novel cytoskeletal protein specific for smooth muscle cells

The characterization of a novel 59-kD cytoskeletal protein is described. It is exclusively observed in smooth muscle cells by Northern blotting and immunohistochemical analysis and therefore designated "smoothelin." A human smooth muscle cDNA library was screened with the monoclonal antibody R4A, and a full-size cDNA of the protein was selected. The cDNA was sequenced and appeared to contain a 1,113-bp open reading frame. Based on the cDNA sequence, the calculated molecular weight of the polypeptide was 40 kD and it was demonstrated to contain two N-glycosylation sites. Computer assisted analysis at the protein level revealed a 56-amino acid domain with homologies of approximately 40% with a sequence bordering the actin-binding domains of dystrophin, utrophin, beta-spectrin and alpha-actinin. In situ hybridization demonstrated that human smoothelin is encoded by a single copy gene which is located on chromosome 22. Immunohistochemistry and Western blotting revealed synthesis of smoothelin in smooth muscle of species evolutionarily as far apart as human and teleost. Northern blotting indicated that sequence as well as size of the mRNA (approximately 1,500 bases) are conserved among vertebrates. Cell fractionation studies and differential centrifugation showed that the protein cannot be extracted with Triton X-100, which indicates that it is a part of the cytoskeleton. Transfection of the human cDNA into smooth muscle cells and COS7 cells produced a protein of 59 kD, which assembled into a filamentous network. However, in rat heart-derived myoblasts association with stress fibers was most prominent. Smoothelin was not detected in primary or long term smooth muscle cell cultures. Also, transcription of smoothelin mRNA was almost instantly halted in smooth muscle tissue explants. We conclude that smoothelin is a new cytoskeletal protein that is only found in contractile smooth muscle cells and does not belong to one of the classes of structural proteins presently known.

Epidermal differentiation in the human external auditory meatus

The differentiation of epidermis in the various parts of the human ear canal was documented on the basis of cytokeratin (Ck) expression patterns. Immunohistochemistry was performed on cryostat sections of normal meatal skin using a comprehensive panel of monospecific Ck antibodies representing the main lines of epithelial differentiation. The epidermis of the cartilaginous part showed a Ck profile characteristic of normal skin type differentiation. The deep meatal skin, including the tympanic membrane, showed a peculiar type of differentiation: in addition to epidermal Cks, hyperproliferation-associated Cks 6, 16, and 17 were expressed in the suprabasal cells, while the simple epithelia cell marker Ck 19 was found in the basal cells. The presence of hyperproliferative Cks in the deep meatal skin could only partly be related to areas of proliferative activity. Keratinocytes, which express markers of hyperproliferation, are migratory. Therefore, their presence in the meatal skin is likely to be related to the peculiar pattern of keratinocyte migration, the purpose of which is to keep the meatus free from desquamation products.

Human multidrug resistance 3-P-glycoprotein expression in transgenic mice induces lens membrane alterations leading to cataract

We have generated mice transgenic for a human multidrug resistance (MDR)3 mini-gene driven by a hamster vimentin promoter. The MDR3 gene encodes a P-Glycoprotein that resembles the mouse multidrug resistance 2 P-Glycoprotein shown to be involved in the translocation of the phospholipid phosphatidylcholine through the hepatocyte canalicular membrane (Smit et al., 1993. Cell. 75:451-462). The vimentin promoter drives expression of the MDR3 transgene in mesenchymal tissues and in the eye lens. We show here that the presence of human multidrug resistance 3 P-Glycoprotein in the lens results in a severe lenticular pathology. Lens structural abnormalities initiate at a late embryonic stage and increase during postnatal lens development. Differentiation of the primary fibers is affected, and the terminal differentiation of the lens epithelium into secondary fibers is also perturbed. The ultrastructural alterations, particularly of the lens plasma membranes, resemble those identified in congenital mouse osmotic cataract.

Differential processes of vascular smooth muscle cell differentiation within elastic and muscular arteries of rats and rabbits: an immunofluorescence study of desmin and vimentin distribution

Two main populations of smooth muscle cells exist in the arterial media of adult mammals with respect to expression of two intermediate filament proteins: vimentin-positive/desmin-negative cells (V+/D-) and vimentin-positive/desmin-positive ones (V+/D+). However, it is still not understood how this phenotypic diversity is established. Since the proportion and the distribution patterns of the two muscle cell populations depend both on the type of blood vessel and the species examined, the aim of the present study was to determine and to compare their developmental origin in various artery segments from two different species. Using confocal scanning laser microscopy and sections stained by means of immunofluorescence, the distribution patterns of desmin and vimentin were compared in transverse sections of thoracic and abdominal aortas (elastic arteries) and of the femoral artery (muscular artery) of newborn and adult rats (n = 12) and rabbits (n = 12). The comparison of sections labelled with specific antibodies showed the existence of a subpopulation of smooth muscle cells in the aortas, but not in the femoral artery, which expressed desmin in newborns but not in adults. These data suggest that the phenotype of smooth muscle cells in elastic arteries but not in muscular arteries is modulated during development.

Immunohistochemical distribution pattern of intermediate filament proteins in 50 feline neoplasms

Twenty-eight epithelial and 22 nonepithelial feline tumors were studied immunohistochemically. Epithelial tumors were 10 squamous cell carcinomas, two basal cell tumors, two sebaceous gland carcinomas, three apocrine gland carcinomas, three thyroid papillary carcinomas, one thyroid solid carcinoma, one renal clear cell carcinoma, one renal papillary carcinoma, one endometrial carcinoma, and four lung bronchioloalveolar carcinomas. Nonepithelial tumors were 10 fibrosarcomas, one liposarcoma, one leiomyosarcoma, one rhabdomyosarcoma, one hemangiosarcoma, two mast cell tumors, one osteosarcoma, three melanomas, and two lymphomas. Commercially available antibodies directed against high- and low-molecular-weight keratins (keratin, RCK-102, NCL-5D3), vimentin, desmin, glial fibrillary acidic protein (GFAP), and neurofilament intermediate filament (IF) proteins were used in the avidin-biotin-peroxidase complex technique on formalin-fixed, paraffin-embedded tumor tissue samples. All epithelial tumors except the endometrial carcinoma expressed some type of keratin protein. Squamous cell carcinomas expressed high-molecular-weight keratins exclusively. Coexpression of high- and low-molecular-weight keratins was observed in one basal cell tumor, sebaceous and apocrine adenocarcinomas, and thyroid, renal, and lung carcinomas. In addition to keratins, vimentin immunoreactivity was found in all basal cell tumors, all sebaceous gland, thyroid papillary, renal, and lung adenocarcinomas, and one of the apocrine gland adenocarcinomas. Immunoreactivity with GFAP antibody was found in one basal cell tumor and one sebaceous gland adenocarcinoma. The endometrial carcinoma did not react with any of the antibodies applied. Nonepithelial tumors analyzed expressed either vimentin (fibrosarcomas, liposarcoma, haemangiosarcoma, mast cell tumors, osteosarcomas, melanomas) or vimentin and desmin (leiomyosarcoma, rhabdomyosarcoma, one fibrosarcoma) IF proteins exclusively. Lymphomas did not react with any of the antibodies employed. These findings indicate that IF proteins antibodies can be included in diagnostic panels of antibodies for immunocharacterization of feline tumors. In addition, they can be used as a basis for the diagnoses of poorly differentiated or undifferentiated feline neoplasms.

Epitope mapping of monoclonal antibodies to keratin 19 using keratin fragments, synthetic peptides and phage peptide libraries

To generate tools for monitoring processing and folding in keratin intermediate filaments, a group of monoclonal antibodies reacting with the intermediate filament protein keratin 19 were studied using different approaches to define the structure and localization of their epitopes. The binding pattern to bacterially expressed human keratin 19 fragments allowed the definition of minimal amino acid sequences required for antibody binding. The screening of overlapping 15-residue peptides confirmed and further specified the epitope locations for a subset of the tested antibodies. In addition, the epitope of an antibody with apparent species-restricted specificity (LE64) was revealed by isolating and characterizing a full-length keratin 19 clone from a PtK2 cDNA library. Taken together with species cross-reactivity of individual antibodies and sequence information obtained by probing a phage display library, specific amino acid residues could be highlighted as likely to be involved in the antibody binding.

Immunocytochemical characterization of explant cultures of human prostatic stromal cells

The study of stromal-epithelial interactions greatly depends on the ability to culture both cell types separately, in order to permit analysis of their interactions under defined conditions in reconstitution experiments. Here we report the establishment of explant cultures of human prostatic stromal cells and their immunocytochemical characterization. As determined by antibodies to keratin and prostate specific acid phosphatase, only small numbers (< 5%) of epithelial cells were present in primary cultures; subsequent passaging further reduced epithelial cell contamination. Antibodies against intermediate filament proteins (keratins, vimentin, and desmin) and smooth muscle actin microfilaments demonstrated that stromal cells from benign prostatic hyperplasia and prostate carcinoma differed in regard to their differentiation markers. Two contrasting phenotypes were identified in cultures derived from these two different lesions: One exhibiting fibroblastic features, was predominant in cultures derived from benign lesions and a second, showing varying degrees of smooth muscle differentiation, was more abundant in carcinoma-derived cultures. These findings are indicative of a remarkable divergence in the stromal-epithelial relationships associated with these pathological conditions and may provide us with a potential tool for studying these processes.

Chronic hibernating myocardium: interstitial changes

Chronic left ventricular dysfunctional but viable myocardium of patients with chronic hibernation is characterized by structural changes, which consist of depletion of contractile elements, accumulation of glycogen, nuclear chromatin dispersion, depletion of sarcoplasmic reticulum and mitochondrial shape changes. These alterations are not reminiscent of degeneration but are interpreted as de-differentiation of the cardiomyocytes. The above mentioned changes are accompanied by a marked increase in the interstitial space. The present study describes qualitative and quantitative changes in the cellular and non-cellular compartments of the interstitial space. In chronic hibernating myocardial segments the increased extracellular matrix is filled with large amounts of type I collagen, type III collagen and fibronectin. An increase in the number of vimentin-positive cells (endothelial cells and fibroblasts) compared with normal myocardium is seen throughout the extracellular matrix. The increase in interstitial tissue is considered as one of the main determinants responsible for the lack of immediate recovery of contractile function after restoration of the blood flow to the affected myocardial segments of patients with chronic left ventricular dysfunction.

A novel IRMA and ELISA for quantifying cytokeratin 8 and 18 fragments in the sera of healthy individuals and cancer patients

Cytokeratins 8 and 18 are most frequently co-expressed in simple epithelia and carcinomas. Fragments of these cytokeratins are released into the systemic circulation where they can be quantified and utilized as tumour markers. The present paper reports on a solid-phase sandwich monoclonal immunoassay, considered "epithelial tissue-specific", which recognizes fragments of human cytokeratins 8 and 18 of different sizes (10-50 kD). The evaluated ELISA and IRMA assays exhibited a detection limit of 0.1 microgram 1-1 and characteristically demonstrated a within-assay coefficient of variation (CV) of 1-4% and a between-assay CV of 3-5%. The long-term (300 days) repeatability of lyophilized samples tested in the assay was estimated to have a less than 10% CV. Of apparently healthy individuals, 95% were found to have serum concentrations of less than 0.95 micrograms 1-1. A highly significant difference was found between apparently healthy individuals and pancreatic cancer patients. Patients with metastatic disease showed a sensitivity of 93% and those with local disease 83%, at 95% specificity. This TPAcyk assay revealed good correlation (0.98) with the TPS assay detecting the specific M3 epitope of the tissue polypeptide antigen. The correlation with the long established polyclonal assay of tissue polypeptide antigen (TPA) was estimated to be 0.9.

Immunophenotyping of congenital myopathies: disorganization of sarcomeric, cytoskeletal and extracellular matrix proteins

We have studied the expression and distribution patterns of the intermediate filament proteins desmin and vimentin, the sarcomere components titin, nebulin and myosin, the basement membrane constituents collagen type IV and laminin, and the reticular layer component collagen type VI in skeletal muscle of patients with "classic" congenital myopathies (CM), using indirect immunofluorescence assays. In all biopsy specimens obtained from patients with central core disease (CCD), nemaline myopathy (NM), X-linked myotubular myopathy (XLMTM) and centronuclear myopathy (CNM), disease-specific desmin disturbances were observed. Vimentin was present in immature fibres in severe neonatal NM, and as sarcoplasmic aggregates in one case of CNM, while the amounts of vimentin and embryonic myosin, observed in XLMTM, decreased with age of the patients. Abnormal expression of myosin isoforms was found in several CM biopsies, although the organization of myosin and other sarcomere components was rarely disturbed. Basement membrane and reticular layer proteins were often prominently increased in severe cases of CM. We conclude that (i) desmin is a marker for individual types of CM and might be used for diagnostic purposes; (ii) the expression patterns of the differentiation markers desmin, vimentin and embryonic myosin in XLMTM, point either to a postnatal muscle fibre maturation or to a variable time-point of maturational arrest in individual patients; (iii) the correlation between the distribution patterns of extracellular matrix proteins and clinical presentation points to a role of these proteins in pathophysiology of CM.

Repeated tape stripping of normal skin: a histological assessment and comparison with events seen in psoriasis

The aim of the present study was to investigate the response of normal human skin to repeated courses of Sellotape stripping. The skin of healthy volunteers was stripped five times at 24-h intervals. Skin biopsies were taken before stripping (day 0) and on days 2, 4, 7 and 10. The responses were studied using H & E staining and an immunohistochemical analysis of several aspects of epidermal proliferation and keratinization. Although increased proliferation (nuclear binding to Ki-67 binding), acanthosis and parakeratosis were observed, the overall histological picture did not resemble psoriatic histology completely: no micropustules of Kogoj and no thinning of the suprapapillary plate were observed. Involucrin staining followed the recruitment of cycling epidermal cells showing a statistically significant elevation of positive cell layers from day 2 onwards. Filaggrin expression showed an increase from day 2 onwards, which was statistically significant on day 7 and day 10. Using the anti-keratin antibodies KS8.12 (K13 and K16) and RKSE60 (K10) we observed a fast induction of K13/K16 expression, while the staining of keratin 10 showed the same overall intensity at different time intervals. In conclusion, the response to repeated courses of tape stripping provides an adequate model for studies on epidermal proliferation, hypergranulosis and hyperkeratosis. This approach causes a more prolonged induction of these phenomena than a single course of stripping. In contrast to the situation following a single course of stripping, repeated tape stripping induced the expression of filagrin. Therefore the repeated tape stripping model is less compatible with psoriasis than a single course of stripping.

Keratinocyte differentiation in psoriatic scalp: morphology and expression of epithelial keratins

The morphology of hair follicles was examined in psoriatic scalp biopsies and compared with normal scalp. In scalp psoriasis the lower outer root sheath and hair matrix were not affected by the psoriatic changes, although there was an irregular expansion in the proximal lower outer root sheath. This area has been characterized, by the presence of keratin K19-containing cells, as the putative stem cell region. In addition, marked shrinkage of the sebaceous glands was seen in the psoriatic scalp, as previously reported. A panel of monospecific monoclonal antibodies to individual epithelial keratins was used to analyse scalp specimens immunohistochemically. Keratin expression in scalp was generally unaffected by psoriasis, except for widespread expression of suprabasal keratins K16 and K17 in suprabasal interfollicular psoriatic scalp epidermis. Simple epithelial keratins K8 and K18 were not found in follicular epithelium from either normal or psoriatic scalp, using multiple monospecific antibodies. This study shows that keratin K17 is induced suprabasally during epidermal hyperproliferation, and cannot therefore be considered a hair follicle-specific keratin.

Are most intraocular "leiomyomas" really melanocytic lesions?

BACKGROUND

Intraocular smooth muscle tumors have long been a subject of controversy. The advent of immunohistochemistry with antibodies against HMB-45, S-100, smooth muscle actin, desmin, and vimentin has helped greatly in the distinction between smooth muscle tumors and melanocytic lesions.

METHODS

Twenty-seven archival tissue blocks from patients who had had intraocular leiomyomas or leiomyosarcomas diagnosed were located and fresh sections cut and stained for the above markers. The cases constituted 24 iris lesions and 3 ciliary body lesions.

RESULTS

All 24 iris tumors were reclassified as iris melanocytic lesions. Two of the three ciliary body leiomyomas retained their classification, and the third was reclassified as a spindle B-cell melanoma.

CONCLUSION

The authors suggest that intraocular leiomyomas are much rarer than previously suggested and that many of the cases previously reported in the literature are open to question.

Intermediate filaments in oral neoplasia. I. Oral cancer and epithelial dysplasia

The major value of intermediate filaments (IFs) in biological and applied research lies in their high order of cell and tissue specificity. This is particularly well illustrated in keratin (K) expression in various oral epithelia. Although the original class of IF is usually conserved in tissues after neoplastic transformation, epithelia show a tendency to shift their pattern of keratin expression in a manner which, while not predictable with precision, may sometimes be of diagnostic or prognostic significance. This review compares the keratins in normal oral epithelia, which show a mainly site-dependent expression, with those in squamous cell carcinoma. Key changes in the latter are the presence of simple epithelial keratins, K8 and K18 (occasional K7), reduced expression of differentiation-linked keratins (K1, K10, K4 and K13) and a tendency for down-regulation of primary keratins, K5 and K14. Moderate and severe dysplasias also tend to exhibit K8 and K18 with concomitant disordered expression of differentiation-linked keratins. There are reports of similar changes after neoplastic transformation in other mucosal sites and skin. Before this information can be applied diagnostically in immunocytochemical studies, the anti-keratin antibodies must be fully characterised and their interaction with the relevant tissue, both frozen and conventionally processed, should be evaluated.

S-phase determination of immunoselected cytokeratin-containing breast cancer cells improves the prediction of recurrence

Estimation of S-phase fraction in breast carcinomas with single parameter flow cytometry may include errors due to dilution of cancer cells by host cells. Use of tissue specific markers may to some extent correct for the effect of dilution. S-phase fraction was estimated by flow cytometry with and without immunoselection in 80 DNA-euploid breast carcinomas in stage I-II. The tumor tissue was mechanically disintegrated and fixed in ethanol. A primary antibody, specific for cytokeratins 8 and 18, was added before incubation with the secondary FITC-conjugated antibody. S-phase fraction was calculated for both the gated (cytokeratin-positive) and the ungated cell population. An increasing proportion of tetraploid cells compared to diploid cells was found when the immunoselection method was used. The gated population tended to have a higher S-phase fraction than the ungated population. In univariate analysis S-phase fraction estimated from both ungated and gated cell populations yielded significant information for predicting recurrence when stratified for tumor size and nodal status. In bivariate analysis S-phase fraction of the gated population contributed prognostic information in addition to S-phase fraction of the ungated population when both variables were included in the analysis. Our conclusion is that S-phase fraction calculated from cytokeratin-positive cells provides prognostic information in addition to ungated S-phase values in DNA euploid breast carcinomas.

Immunohistochemical distribution of vimentin, desmin, glial fibrillary acidic protein and neurofilament proteins in feline tissues

The immunohistochemical distribution pattern of vimentin, desmin, glial fibrillary acidic protein and neurofilaments intermediate filament proteins has been analyzed in a wide range of formalin fixed, paraffin embedded tissues using polyclonal and monoclonal antibodies raised against non-feline antigens. The vimentin antibody reacted with mesenchymal cells, the desmin antibody with striated and smooth muscle fibres, the glial fibrillary acidic protein antibody with glial cells in the central and peripheral nervous system, and the neurofilament proteins antibody with neuronal cell bodies and processes. In addition, some epithelial cells were vimentin positive, perisinusoidal liver cells were desmin positive, and basal/myoepithelial cells of the mammary gland, and luteinic cells were glial fibrillary acidic protein positive. These staining patterns of feline tissues are basically similar with respect to that of corresponding tissues in other mammalian species for each of the four intermediate filament proteins studied, but some differences have been also noticed. This study confirms the broad interspecies cross-reactivity of intermediate filament proteins antisera and demonstrates their capability to differentiate particular types of feline cells and tissues.

Primary mesenchymal (nonangiomatous/nonlymphomatous) neoplasms occurring in the canine spleen: anatomic classification, immunohistochemistry, and mitotic activity correlated with patient survival

Surgical submissions from canine splenectomy cases spanning a 3-year period (1988-1990) were evaluated. Eighty seven neoplasms of the spleen considered to be of nonangiomatous and nonlymphomatous origin were selected for morphologic classification, mitotic index determination, immunohistochemical analysis, and patient survival determination. In 76/87 cases, patient survival information was available, and the mitotic index was determined in 83/87 cases. Immunohistochemistry for selected antigens (vimentin, desmin, smooth muscle actin, myosin, and factor VIII-related antigen) was performed in 58/87 of the cases. Morphologic classification of these lesions in standard HE preparations yielded the following neoplastic groups: fibrosarcoma (19/87), undifferentiated sarcoma (19/87), leiomyosarcoma (14/87), osteosarcoma (8/87), mesenchymoma (7/87), myxosarcoma (6/87), histiocytic sarcoma (6/87), leiomyoma (3/87), lipoma-myelolipoma (2/87), liposarcoma (2/87), and malignant fibrous histiocytoma (1/87). A lack of distinct morphologic characteristics among many of the neoplasms that were classified as either fibrosarcoma, leiomyosarcoma, or undifferentiated sarcoma contrasted these groups with the relatively unambiguous features that distinguished the other sarcoma groups. Using immunohistochemical staining for muscle-specific antigens (desmin, smooth muscle actin, and myosin), specific staining often overlapped extensively within the neoplastic groups of fibrosarcomas, leiomyosarcomas, and undifferentiated sarcomas, suggesting either ambiguous morphologic findings or the possibility of a common histogenesis from smooth muscle trabeculae or a distinct population of splenic myofibroblasts. The biological behavior of all tumors examined could be placed into three categories of patient survival: (1) benign, noninvasive tumors (leiomyoma, lipoma) with prolonged survival intervals; (2) malignant tumors (fibrosarcoma, undifferentiated sarcoma, leiomyosarcoma, osteosarcoma, myxosarcoma, histiocytic sarcoma, and liposarcoma), showing severely truncated survival (median 4 months with 80-100% mortality after 12 months; and (3) intermediate survival periods (median 12 months with 50% 1 year survival) attributed to a single group of neoplasm, the mesenchymomas. The biological behavior of primary splenic nonangiomatous, nonlymphomatous sarcomas was most closely correlated with observed mitotic index. Splenic neoplasms of this type with a mitotic index < 9 showed significantly (P < 0.0001) longer survival intervals than those with an index > 9. With the exception of osteosarcoma, all anatomically defined tumor groups contained one or more specimens with a mitotic index < 9. The clinical prognosis given for splenic sarcomas should be modified according to the mitotic index as a predictive value for patient survival.

Sebaceous epithelioma

An 83-year-old woman had developed an asymptomatic, yellowish, dome-shaped skin tumor on her scalp which had enlarged for a period of 60 years to 10 x 10 x 10 mm in size. Histopathologically, the tumor consisted of undifferentiated basaloid cells, differentiated sebaceous cells and transitional cells. Although the basaloid cells resembled those of basal cell epithelioma (BCE), the tumor was distinct from BCE in the following points; existence of cystic spaces, no peripheral palisading, no proliferation of connective tissue stroma, and no tendency toward local invasion. Immunohistochemical studies using antikeratin monoclonal antibodies revealed that the tumor contained both the keratin types of BCE and of sebaceous glands. Electron microscopically, the tumor cells contained lipid droplets and keratohyaline granules in their cytoplasm. It is suggested that "sebaceous epithelioma" is a benign skin tumor which may be distinguished cytologically from BCE.

Immunohistochemistry with keratin, vimentin, desmin, and alpha-smooth muscle actin monoclonal antibodies in canine mammary gland: normal mammary tissue

Normal canine mammary gland tissue was studied immunohistochemically with monoclonal antibodies (MoAbs) directed against various human keratin types, vimentin, desmin, and alpha-smooth muscle actin. Both ductal and alveolar luminal cells were immunoreactive with MoAbs recognizing respectively human keratins no. 7, 8, 18 and 19. In addition, some ductal luminal cells were labelled with a keratin 4 and a keratin 10 MoAb. Basal/myoepithelial cells were immunoreactive only with MoAbs directed against keratin 14, keratins 14 and 17, and alpha-smooth muscle actin. The vimentin MoAb merely labelled solitary loose intraluminal cells representing macro-phages or sloughed epithelial cells. These findings correspond largely to observations made in human breast tissue.

Spindle cell hemangioendothelioma: a report of two cases

Two cases of spindle cell hemangioendothelioma (SCH) are reported. One of the patients was a 16 year old Japanese female, who had been suffering from Ollier's disease (multiple enchondromatosis) since 3 years of age and had developed multiple SCH in the right leg at the age of 11 years. Spindle cell hemangioendothelioma lesions coincided with the site of enchondromatosis and increased in number thereafter. This is the first report of Ollier's disease complicated with multiple SCH. Another patient, a 33 year old Japanese female, who was a carrier of hepatitis B virus (HBV), developed solitary SCH in the lateral aspect of the right ankle where a lipoma was extirpated 10 years previously. Tumor cells of both cases were composed of four cell types: (i) spindle cells; (ii) epithelioid cells; (iii) vacuolated endothelial cells; and (iv) usual endothelial cells. Endothelia in the cavernous area and vacuolated cells reacted to Ulex europaeus agglutin 1 (UEA-I), factor VIII-related antigen and vimentin. Spindle cells and epithelioid cells reacted only to vimentin.

Intermediate filament protein expression in early developmental stages of the mouse. A confocal scanning laser microscopy study of in vitro fertilized and in vitro cultured pre-implantation mouse embryos

Expression patterns of intermediate filament proteins have been studied during early mouse embryo development. For this purpose, pre-implantation embryos at different stages of development after in vitro fertilization were studied using antibodies to cytokeratins, vimentin and lamins, using the indirect immunofluorescence assay. The levels of expression were quantitated and localization of the protein constituents was assessed by means of confocal scanning laser microscopy. Our studies showed that, although the embryos grew in culture, vimentin could not be detected in a filamentous organization. Immunofluorescence for cytokeratins was only positive from the 8-cell stage onwards. In the morula stage an increased level of cytokeratin expression was observed with a transitional staining pattern, combining a filamentous and a diffuse occurrence. In the blastocyst stages profound cytokeratin filaments were seen in trophoblast cells but not in the inner cell mass. When the cytokeratin subtypes were analysed separately, it became apparent that expression levels of cytokeratins 8 and 18 increased gradually up to a filamentous pattern in the blastocyst stage. Cytokeratins 7 and 19, although elevated in the latter stage and showing a filamentous distribution, were not found as prominently as cytokeratins 8 and 18. A-type as well as B-type lamins could be detected in all developmental stages examined, as a faintly reactive nuclear lamina. In blastocysts both lamin types were detected in trophoblast as well as in inner cell mass.

Regulation of vimentin expression in cultured epithelial cells

Most cell types start expressing vimentin when brought into tissue culture. Using both vimentin-expressing (HeLa) and vimentin-negative (MCF-7) epithelial cell lines, we have identified the cis-regulatory DNA elements involved in this process. Sequences located 1.1-0.6 kb upstream of the vimentin transcription-initiation site strongly enhance expression in HeLa cells, but are silenced in MCF-7 cells. Other regulatory elements in the vimentin promoter (an enhancer 3.2-2.6 kb upstream and a minimal promoter region including the CAAT-box) are potentially active in both cell types, but are silenced by the 0.5-kb fragment in MCF-7 cells. Deletion of this fragment restores transcriptional activity of a transfected vimentin promoter. Our data indicate that a double AP 1/jun-binding site present in the 0.5-kb fragment mediates the induction of vimentin expression in cultured epithelial cells, while silencing sequences located within the same fragment are responsible for the absence of vimentin expression in MCF-7 cells. In contrast to MCF-7 cells, a transfected vimentin promoter and gene are transcriptionally active in the vimentin-negative epithelial cell line T24. Transfection studies show that type-III-intermediate-filament expression is not impaired at any level in these cells. Upon transfection and expression of a desmin construct in T24 cells not only desmin, but also vimentin was detected. Both proteins assembled into intermediate filaments. This induction of vimentin expression appeared to be regulated at the post-transcriptional level.

Vimentin and desmin expression in degenerating and regenerating dystrophic murine muscles

The distribution of the intermediate filament proteins (IFP) desmin and vimentin was studied in gastrocnemius, plantaris and soleus muscles of the dystrophic mouse strain ReJ 129 during postnatal development. Special attention was paid to the overall morphological changes in the distribution of these cytoskeletal constituents in degenerating and regenerating muscle fibres. In contrast to their normal counterparts, the dystrophic mice (ReJ 129 dy/dy) appeared to develop four types of distinct muscle fibres with immunohistochemically detectable aberrant IFP patterns. The distribution of desmin IFP differed in the dystrophic muscle fibres as compared to the normal fibres in that juxtanuclear aggregates of IFP were frequently seen. In contrast to the recent literature we conclude that these cells are regenerated myofibres exhibiting defective nuclear migration.

Keratin and vimentin distribution patterns in the epithelial structures of the canine anal region

The intermediate filament labeling pattern of the epithelial structures of the canine anal region was studied with different polypeptide specific keratin monoclonal antibodies (MoAbs) and with a monoclonal and polyclonal vimentin antibody. The epithelial structures in this region could be discriminated and characterized by differences in their keratin staining pattern. The basal cells in the different epithelial structures showed a similar staining pattern characterized by reactivity with MoAbs staining keratins 5, 8, 14, and 17. Columnar epithelial cells showed a completely different phenotype mostly characterized by reactivity with MoAbs staining keratins 7, 5, 8, 18, and 19. A restricted number of differentiated perianal gland cells showed perinuclear vimentin staining. Myoepithelial cells did not stain for vimentin, but, as other basal cells, were positive for MoAbs staining keratins 5, 8, 14, and 17.

Immunohistochemical analysis of the cytokeratin expression in middle ear cholesteatoma and related epithelial tissues

Immunohistochemical investigations were carried out to determine the pattern of cytokeratin (CK) expression in middle ear cholesteatoma and related epithelia. Using monoclonal antibodies specific for CK chains and the indirect immunoperoxidase technique, we examined 10 CK polypeptides for expression. The external stratified squamous epithelium of the tympanic membrane generally expressed CKs 5, 10, and 14. In addition, basal keratinocytes in the annular region of the pars tensa expressed CK 19 (a simple epithelium marker), while suprabasally the hyperproliferative marker CK 16 was expressed. These data reflect the unusual proliferative nature of this region. The unexpected appearance of CK 16 (known to have a limited distribution in healthy epidermis) clearly relates to its expression in the neighboring deep meatus. The medial simple epithelium of the eardrum revealed mucosal CKs 7, 8, 14, 18, and 19. Acquired cholesteatoma lesions, besides CKs 5, 10, and 14, consistently expressed CK 16 in suprabasal layers. These results constitute the first direct molecular evidence for the hyperproliferative nature of the cholesteatoma matrix. Overall, our CK data suggest that aural cholesteatoma lesions and epidermal tissue in this area are related. However, they do not explain the mechanism(s) by which the eardrum or meatal epithelia might invade the middle ear cavity. Congenital cholesteatomas expressed CKs 5, 10, 14, and 16 equally. These CK data do not support the idea of a metaplastic origin from middle ear mucosa; instead, they suggest activation of an ectodermal rest in the middle ear cavity.

Changes in cytokeratin expression during the development of the human oral mucosa

The changes in cytokeratin expression by the developing oral mucosa of 10 to 23-week-old human fetuses were studied by indirect immunofluorescence using a panel of 15 monoclonal antibodies. The lining and masticatory mucosae were incompletely differentiated in 10-wk fetuses, since they expressed identical patterns of cytokeratins (CK 4, 5, 8, 13, 18, 19 and probably CK 14, 16, 17) very similar to that of adult alveolar mucosa. The main difference was the presence of cytokeratins 8, 18 and 19 in embryonic tissues. Cytokeratins 1, 2, 10 and 11 began to appear in gingival and hard palate epithelium from wk 11, predicting the differentiation of the masticatory mucosa by wk 16. The patterns of cytokeratin expression in the 23-wk fetus in the lining and masticatory mucosae appear to be different. In lining mucosa, the only difference from the 10th wk is a decrease in cytokeratins 8, 18 and 19, whereas the pattern of cytokeratin expression in masticatory mucosa (CK 1, 2, 4, 5, 8, 10, 11, 13, 18, 19 and probably CK 14, 16 and 17) is now very near that of adult gingiva. This pattern appears, as in the adult, to be similar to that of the epidermis in the same period.

Differentiation of human skeletal muscle cells in culture: maturation as indicated by titin and desmin striation

This report describes a phenotyping study of differentiating human skeletal muscle cells in tissue culture. Satellite cells (adult myoblasts), isolated from biopsy material, showed a proliferative behaviour in high-nutrition medium, but fused to form myotubes when grown in low-nutrition medium. The expression and structural organization of the intermediate filament proteins desmin and vimentin as well as the sarcomeric constituents alpha-actin, alpha-actinin, nebulin, myosin and especially titin during myofibrillogenesis in vitro, were studied by means of indirect immunofluorescence assays. The proliferating myoblasts contained both desmin and vimentin, alpha-actinin and the filamentous form of actin. Shortly after the change of medium, expression of titin, sarcomeric myosin and skeletal muscle alpha-actin was found in mononuclear cells in a diffuse, filamentous (titin, myosin, alpha-actin) or punctate (titin, myosin) pattern. Four to 10 days after the medium change, mature myotubes showed desmin, titin, alpha-actinin, nebulin, sarcomeric myosin and actin cross-striations, while vimentin was no longer detected. We conclude that human skeletal muscle cell cultures are an appropriate model system to study the molecular basis of myofibrillogenesis. Especially the presence of desmin in a striated fashion points to a high degree of maturation of the muscle cell cultures.

Monoclonal antibody analysis of keratin expression in carcinomas of sweat glands

Characteristics of keratins of five carcinomas of sweat gland origin were immunohistochemically investigated with several antikeratin monoclonal antibodies with differing specificities. Specimens were obtained from two cases of mucinous carcinoma of the skin, two cases of classic type of eccrine adenocarcinoma, and a case of eccrine porocarcinoma. The tumor cells of mucinous carcinoma expressed only simple epithelial keratins. In a case of eccrine adenocarcinoma, simple epithelial keratin 19 was diffusely expressed. The expression of the other simple epithelial keratins was confined to the luminal cells, whereas the remaining tumor cells further expressed stratified epithelial keratins. Eccrine porocarcinoma and a second case of eccrine adenocarcinoma did not express simple epithelial keratins, although stratified epithelial keratins were diffusely expressed. These data suggest that carcinomas of sweat glands express various combinations of simple and stratified epithelial keratins. Development of additional data along these lines may help to further define their classification.

Epidermal proliferation and keratinization following standardized elicitation with diphenylcyclopropenone

Diphenylcyclopropenone (DCP) was applied to the upper arms of five alopecia areata patients using 10% of the concentration that had been applied previously to the scalp during topical immunotherapy. DCP applied in this concentration evoked a mild eczematous reaction. Biopsies were taken before DCP application and after 24, 48 and 96 h. A large increase in T-lymphocytes and CD14-positive cells in the dermis was seen after 24 h. Migration of these cells into the epidermis was mainly observed during the first 48 h. This was followed by epidermal proliferation as assessed by the number of Ki-67-positive nuclei and the degree of Ks8.12-binding. Both showed their main increase after 48 h; but after 24 h the increase of Ki-67-positive nuclei was significant (P < 0.04). Involucrin and filaggrin showed a gradual increase which became substantial after 96 h (both P < 0.04). As the invasion of inflammatory cells into the epidermis preceded the main increase in epidermal proliferation, cytokines are suggested as possible mediators for the initial phase of the proliferative response after DCP application.