Expression of glial filament protein (GFP) in nerve sheaths and non-neural cells re-examined using monoclonal antibodies, with special emphasis on the co-expression of GFP and cytokeratins in epithelial cells of human salivary gland and pleomorphic adenomas

Plasticity of endometrial epithelial and stromal cells-A new approach towards the pathogenesis of equine endometrosis

Equine endometrosis, a frequent cause of subfertility, is characterized by periglandular fibrosis, and no treatment exists. Endometrial biopsies not only contain diseased glands, but also contain healthy glands and stroma. Myoepithelial (ME) and myofibroblastic (MF) markers are calponin, smooth muscle actin (SMA), desmin and glial fibrillary acidic protein (GFAP). Epithelial vimentin expression indicates epithelial to mesenchymal transition (EMT). The aim of this immunohistochemical study was to investigate whether biopsies with endometrosis express MF and ME markers and vimentin. Compared to healthy areas, significantly higher percentages of endometrotic glands were lined by calponin- and vimentin-positive epithelial cells, whereas periglandular fibrosis contained significantly higher percentages of stromal cells positive for vimentin, desmin and SMA and significantly less calponin-positive stromal cells. The rare GFAP expression was restricted to endometrotic glands. Of these, the most frequent features of endometrotic glands were higher percentages of SMA- and vimentin-positive stromal cells and the prominent epithelial calponin staining that occurred in 100%, 93% and 95% of examined biopsies. Results indicate plasticity of equine endometrial epithelial and stromal cells. Particularly, endometrotic glands show evidence for ME differentiation and EMT. The different expression of MF markers between stromal cells from healthy and endometrotic areas suggests functional differences. The characteristic changes in the expression of SMA, vimentin and calponin between endometrotic glands and healthy areas can be helpful to confirm early stages of endometrosis. The characterization of cellular differentiation may help to decipher the pathogenesis of endometrosis and could lead to therapeutic strategies.

A system for studying mechanisms of neuromuscular junction development and maintenance

The neuromuscular junction (NMJ), a cellular synapse between a motor neuron and a skeletal muscle fiber, enables the translation of chemical cues into physical activity. The development of this special structure has been subject to numerous investigations, but its complexity renders in vivo studies particularly difficult to perform. In vitro modeling of the neuromuscular junction represents a powerful tool to delineate fully the fine tuning of events that lead to subcellular specialization at the pre-synaptic and post-synaptic sites. Here, we describe a novel heterologous co-culture in vitro method using rat spinal cord explants with dorsal root ganglia and murine primary myoblasts to study neuromuscular junctions. This system allows the formation and long-term survival of highly differentiated myofibers, motor neurons, supporting glial cells and functional neuromuscular junctions with post-synaptic specialization. Therefore, fundamental aspects of NMJ formation and maintenance can be studied using the described system, which can be adapted to model multiple NMJ-associated disorders.

Recent molecular approaches to understanding astrocyte function in vivo

Astrocytes are a predominant glial cell type in the nervous systems, and are becoming recognized as important mediators of normal brain function as well as neurodevelopmental, neurological, and neurodegenerative brain diseases. Although numerous potential mechanisms have been proposed to explain the role of astrocytes in the normal and diseased brain, research into the physiological relevance of these mechanisms in vivo is just beginning. In this review, we will summarize recent developments in innovative and powerful molecular approaches, including knockout mouse models, transgenic mouse models, and astrocyte-targeted gene transfer/expression, which have led to advances in understanding astrocyte biology in vivo that were heretofore inaccessible to experimentation. We will examine the recently improved understanding of the roles of astrocytes – with an emphasis on astrocyte signaling – in the context of both the healthy and diseased brain, discuss areas where the role of astrocytes remains debated, and suggest new research directions.

Immunofluorescent spectral analysis reveals the intrathecal cannabinoid agonist, AM1241, produces spinal anti-inflammatory cytokine responses in neuropathic rats exhibiting relief from allodynia

During pathological pain, the actions of the endocannabinoid system, including the cannabinoid 2 receptor (CB(2)R), leads to effective anti-allodynia and modifies a variety of spinal microglial and astrocyte responses. Here, following spinal administration of the CB(2)R compound, AM1241, we examined immunoreactive alterations in markers for activated p38 mitogen-activated protein kinase, interleukin-1β (IL-1β), the anti-inflammatory cytokine, interleukin-10 (IL-10) as well as degradative endocannabinoid enzymes, and markers for altered glial responses in neuropathic rats. In these studies, the dorsal horn of the spinal cord and dorsal root ganglia were examined. AM1241 produced profound anti-allodynia with corresponding immunoreactive levels of p38 mitogen-activated kinase, IL-1β, IL-10, the endocannabinoid enzyme monoacylglycerol lipase, and astrocyte activation markers that were similar to nonneuropathic controls. In contrast, spinal AM1241 did not suppress the increased microglial responses observed in neuropathic rats. The differences in fluorescent markers were determined within discrete anatomical regions by applying spectral analysis methods, which virtually eliminated nonspecific signal during the quantification of specific immunofluorescent intensity. These data reveal expression profiles that support the actions of intrathecal AM1241 control pathological pain through anti-inflammatory mechanisms by modulating critical glial factors, and additionally decrease expression levels of endocannabinoid degradative enzymes.

Lens intermediate filaments

The ocular lens assembles two separate intermediate filament systems sequentially with differentiation. Canonical 8-11 nm IFs composed of Vimentin are assembled in lens epithelial cells and younger fiber cells, while the fiber cell-specific beaded filaments are switched on as fiber cell elongation initiates. Some of the key features of both filament systems are reviewed.

Subtypes of melanocytes and melanoma cells distinguished by their intercellular contacts: heterotypic adherens junctions, adhesive associations, and dispersed desmoglein 2 glycoproteins

In the tissue integration of melanocytes and melanoma cells, an important role is attributed to cell adhesion molecules, notably the cadherins. In cultured melanoma cells, we have previously described a more heterogeneous repertoire of cadherins than normal, including some melanoma subtypes synthesizing the desmosomal cadherin, desmoglein 2, out of the desmosomal context. Using biochemical and immunological characterization of junctional molecules, confocal laser scanning, and electron and immunoelectron microscopy, we now demonstrate homo- and heterotypic cell-cell adhesions of normal epidermal melanocytes. In human epidermis, both in situ and in cell culture, melanocytes and keratinocytes are connected by closely aligned membranes that are interspersed by small puncta adhaerentia containing heterotypic complexes of E- and P-cadherin. Moreover, melanocytes growing in culture often begin to synthesize desmoglein 2, which is dispersed over extended areas of intimate adhesive cell-cell associations. As desmoglein 2 is not found in melanocytes in situ, we hypothesize that its synthesis is correlated with cell proliferation. Indeed, in tissue microarrays, desmoglein 2 has been demonstrated in a sizable subset of nevi and primary melanomas. The biological meanings of these cell-cell adhesion molecule arrangements, the possible diagnostic and prognostic significance of these findings, and the implications of the heterogeneity types of melanomas are discussed.

Morphometrical and neurochemical changes in the anteroventral subdivision of the rat medial amygdala during estrous cycle

The anteroventral subdivision of the medial amygdala (MeAV) is one of the vomeronasal structures involved in the control of hormonally dependent behaviors such as sexual and agonistic behaviors in rats. The present study investigates some anatomical and neurochemical parameters of this nucleus (volume, number of neurons, number of glial elements, and of NADPH-diaphorase-positive neurons) in females in two estrous cycle phases (diestrous and estrous) and in males. We also investigate the possible existence of adult neurogenesis in this nucleus in the females. Results showed that volume and estimated number of Nissl-stained neurons in the MeAV vary with the estrous cycle phase: estrous females have greater values than diestrous females. As a consequence of these variations, there is a transient sex difference between males and diestrous females. Two subpopulations of NADPH-diaphorase-positive neurons were detected: intensely stained and medium stained. The intensely stained neurons were more numerous in the estrous than the diestrous females. Neither BrdU nor GFAP inmunostaining revealed significant differences between the two groups, suggesting that adult cell generation, i.e., increases in the number of glial elements, has no significant role in the changes detected in the number of Nissl-stained sections. In conclusion, the MeAV shows functional diergism, due to plastic changes in the female rat brain probably linked to the increase of estradiol during estrous. Finally, these changes are probably functionally related to changes in the behaviors that are controlled through this nucleus.

Cilia containing 9 + 2 structures grown from immortalized cells

Cilia depend on their highly differentiated structure, a 9 + 2 arrangement, to remove particles from the lung and to transport reproductive cells. Immortalized cells could potentially be of great use in cilia research. Immortalization of cells with cilia structure containing the 9 + 2 arrangement might be able to generate cell lines with such cilia structure. However, whether immortalized cells can retain such a highly differentiated structure remains unclear. Here we demonstrate that (1) using E1a gene transfection, tracheal cells are immortalized; (2) interestingly, in a gel culture the immortalized cells form spherical aggregations within which a lumen is developed; and (3) surprisingly, inside the aggregation, cilia containing a 9 + 2 arrangement grow from the cell's apical pole and protrude into the lumen. These results may influence future research in many areas such as understanding the mechanisms of cilia differentiation, cilia generation in other existing cell lines, cilia disorders, generation of other highly differentiated structures besides cilia using the gel culture, immortalization of other ciliated cells with the E1a gene, development of cilia motile function, and establishment of a research model to provide uniform ciliated cells.

Synemin expression is widespread in liver fibrosis and is induced in proliferating and malignant biliary epithelial cells

The expression profile of intermediate filament proteins provides valuable information on the differentiation of specific cell populations and their contributions to disease. Synemin is one of the few intermediate filament proteins whose expression pattern during pathological situations is poorly characterized. We conducted a systematic immunohistochemical investigation of synemin expression in human liver diseases. In normal liver and in the early prefibrotic phase of chronic viral hepatitis or steatohepatitis, synemin was localized in hepatic stellate cells (HSCs) and vascular cells. Fibrotic or cirrhotic liver disease promoted intense synemin staining of HSCs in parenchymal and fibrous zones. In portal tract fibroblasts, synemin expression was rare under normal conditions but was widespread in severe inflammatory diseases associated with portal expansion, consistent with the notion that some fibrotic reactions involve HSCs, whereas others involve both HSCs and portal fibroblasts. Most sinusoidal endothelial cells were synemin negative in normal liver but were positive in hepatocellular carcinomas. Synemin was also expressed in the epithelial component of the ductular reaction in various liver diseases and in cholangiocarcinoma cells but not in hepatocellular carcinoma cells. Myofibroblasts in stromal reaction to carcinomas were synemin positive. Thus, synemin helps delineate different types of liver fibrotic reactions and provides a marker for sinusoidal capillarization and for proliferating biliary epithelial and cholangiocarcinoma cells.

Inhibition of P53-related apoptosis had no effect on PrPSc accumulation and prion disease incubation time

Results from several laboratories indicate that apoptosis via the P53 pathway is involved in prion disease pathogenesis. Prion diseases, among them scrapie and BSE, are a group of fatal neurodegenerative disorders associated with the conversion of PrP(C) to PrP(Sc), its conformational abnormal isoform. In this work, we tested whether an established anti-apoptotic reagent, PFT, which has been shown in different systems to inhibit P53 activity, can delay the outbreak of prion disease in infected animals. Our findings indicate that although PFT efficiently reduced caspase 3 expression in brains from scrapie sick hamsters, as well as inhibited PrP(Sc) accumulation in cell culture, it had no effect on disease incubation time or PrP(Sc) accumulation in vivo. We conclude that the P53 dependent apoptosis may not be an obligatory mechanism for prion disease-induced cell death.

GFAP immunoreactivity and transcription in trigeminal and dental tissues of rats and transgenic GFP/GFAP mice

Sensory mechanisms in teeth are not well understood and may involve pulpal-neural interactions. Tooth cells that proliferate in vitro have polyclonal immunoreactivity (IR) for glial fibrillary acidic protein (GFAP), growth-associated protein (GAP-43), and vimentin, plus glial-like ion channels. Here, we analyzed GFAP-IR patterns in dental and trigeminal tissues of rats, for comparison with green fluorescent protein (GFP) associated with GFAP transcription in transgenic mice, in order to better characterize glial-like cells in dental tissues. Astrocytes, ganglion satellite cells, and epineurial Schwann cells were demonstrated by anti-GFAP antibodies and GFP-GFAP, as expected. Odontoblasts did not stain by any of these methods and cannot be the glial-like cells. Fibroblasts and undifferentiated mesenchymal cells in pulp had polyclonal GFAP-IR and vimentin-IR, while nerve fibers reacted only with polyclonal antibody. Some Schwann cell subtypes in trigeminal nerve and oral mucosa were positive for GFP and for polyclonal anti-GFAP, but not for monoclonal antibody. In pulp almost all Schwann cells were unstained, but many Schwann cells in periodontal ligament had polyclonal GFAP-IR. These results show greater heterogeneity for Schwann cells than expected, and suggest that the glial-like pulp cells are fibroblasts and/or undifferentiated mesenchymal cells or stem cells. We also found that polyclonal GFAP revealed intermediate filaments in preterminal sensory nerve fibers, thereby providing a useful marker for that neural subregion. GFP transcription by some Schwann cell subtypes in oral mucosae and trigeminal nerve, but not trigeminal root was a novel finding that reveals more complexity in peripheral glia than previously recognized.

Malignant Chondroid Syringoma with Bone Invasion: A Case Report and Review of the Literature

We describe a 27-year-old Japanese female with a recurrent nodule on the left big toe and local bone invasion. Histopathologically, the tumor consisted of nests of atypical cells with few mitotic cells, which partly formed gland-like structures. Areas of myxoid degeneration, positive for Alcian blue staining and that did not stain after they were digested with hyaluronidase, were prominent in the matrix among tumor cells. Positive staining was noted in tumor cells for cytokeratin (AE1+AE3), S-100 protein, neuron specific enolase (NSE), and glial fibrillary acidic protein (GFAP). These findings, especially positive GFAP staining were characteristic and very helpful for the diagnosis of the rare tumor-malignant chondroid syringoma. Based on the previous reports, 39% of cases were found to have metastatic lesions and 22% died of this malignant tumor. There have been no reports reporting effectiveness of chemotherapy and radiotherapy, and an early wide excision with a broad margin may be the most reliable treatment to date.

Salivary-type neoplasms of the breast and lung

Salivary-type tumors occur in multiple sites in the human body, likely related to a basic structural homology between exocrine glands in these different anatomic areas. This paper reviews these salivary gland tumor types in breast tissue and lung. Salivary-type tumors of both breast and lung are relatively uncommon in comparison to their salivary gland counterparts. This may be attributable in part to lack of familiarity with these tumors in extra-salivary sites, and in part to histologic overlap with other primary and metastatic tumor types. Recognition of these entities is improving as the clinical and pathologic features are better delineated, and tumors are more accurately classified. Prediction of malignant behavior is not always possible in these unusual sites. In some instances, such as adenoid cystic carcinoma, behavior is known to differ considerably from that of analogous primary salivary gland tumors and in other instances there are simply too few reported cases to allow for adequate prognostication. In fact, more recent papers discuss the need to consider a spectrum encompassing benign and malignant lesions, in both breast and lung. Of course, some entities show clear-cut evidence of malignancy with documented potential for metastasis, others show bland features and well-reported benign behavior, and the less well-defined entities reside between these two extremes. The molecular pathology of salivary gland tumors has been reasonably well investigated in that location; however; there are few molecular studies devoted to salivary-type tumors of the breast and lung. This represents a potential area for future growth in further clarifying these tumors and their behavior.

Invasive ductal carcinoma of the mammary gland in a mare

A 21-year-old thoroughbred mare had a 35 x 14 x 10 cm mass involving the mammary gland. Metastases were found in the kidneys, lungs, skeletal muscles, and regional lymph nodes. Histopathologic examination of the tumor revealed a ductal solid carcinoma with extensive intraductal and intralobular involvement and focal infiltration of the adjacent stroma. The intralobular neoplasms were divided into irregularly shaped islands and sheets of polygonal and spindle-shaped epithelial cells by thick or thin fibrous connective tissue bundles. The neoplastic cells had a small or moderate amount of cytoplasm that stained faintly with eosin and round or oval hyperchromatic nuclei. Immunohistochemically, the neoplastic cells were strongly positive for Lu-5, weakly positive for AE1/AE3, vimentin, and glial fibrillary acidic protein, and negative for cytokeratin 8, cytokeratin 14, alpha-smooth muscle actin, calponin, and S100. The neoplasm was diagnosed as an invasive ductal carcinoma of the mammary gland with multiple metastases.

Immunocytochemistry of myoepithelial cells in the salivary glands

MECs are distributed on the basal aspect of the intercalated duct and acinus of human and rat salivary glands. However, they do not occur in the acinus of rat parotid glands, and sometimes occur in the striated duct of human salivary glands. MECs, as the name implies, have structural features of both epithelial and smooth muscle cells. They contract by autonomic nervous stimulation, and are thought to assist the secretion by compressing and/or reinforcing the underlying parenchyma. MECs can be best observed by immunocytochemistry. There are three types of immunocytochemical markers of MECs in salivary glands. The first type includes smooth muscle protein markers such as alpha-SMA, SMMHC, h-caldesmon and basic calponin, and these are expressed by MECs and the mesenchymal vasculature. The second type is expressed by MECs and the duct cells and includes keratins 14, 5 and 17, alpha 1 beta 1 integrin, and metallothionein. Vimentin is the third type and, in addition to MECs, is expressed by the mesenchymal cells and some duct cells. The same three types of markers are used for studying the developing gland. Development of MECs starts after the establishment of an extensively branched system of cellular cords each of which terminates as a spherical cell mass, a terminal bud. The pluripotent stem cell generates the acinar progenitor in the terminal bud and the ductal progenitor in the cellular cord. The acinar progenitor differentiates into MECs, acinar cells and intercalated duct cells, whereas the ductal progenitor differentiates into the striated and excretory duct cells. Both in the terminal bud and in the cellular cord, the immediate precursors of all types of the epithelial cells appear to express vimentin. The first identifiable MECs are seen at the periphery of the terminal bud or the immature acinus (the direct progeny of the terminal bud) as somewhat flattened cells with a single cilium projecting toward them. They express vimentin and later alpha-SMA and basic calponin. At the next developmental stage, MECs acquire cytoplasmic microfilaments and plasmalemmal caveolae but not as much as in the mature cell. They express SMMHC and, inconsistently, K14. This protein is consistently expressed in the mature cell. K14 is expressed by duct cells, and vimentin is expressed by both mesenchymal and epithelial cells. After development, the acinar progenitor and the ductal progenitor appear to reside in the acinus/intercalated duct and the larger ducts, respectively, and to contribute to the tissue homeostasis. Under unusual conditions such as massive parenchymal destruction, the acinar progenitor contributes to the maintenance of the larger ducts that result in the occurrence of striated ducts with MECs. The acinar progenitor is the origin of salivary gland tumors containing MECs. MECs in salivary gland tumors are best identified by immunocytochemistry for alpha-SMA. There are significant numbers of cells related to luminal tumor cells in the non-luminal tumor cells that have been believed to be neoplastic MECs.

Intermediate-filament expression in ocular tissue

Intermediate-filament proteins (IFPs) occur in the intracellular cytoskeleton of eukaryotic cells, and their expression in diverse tissues is related both to embryology as well as to differentiation. Although the available information concerning their functional properties in vivo is still incomplete, antibodies against individual IFPs are commonly used in immunohistochemical procedures as markers for differentiation, and these antibodies are of outstanding value in the routine histopathological evaluation of tumor specimens. This review presents a compilation of the currently available data concerning IFP expression in normal and diseased ocular tissues. Representatives of every known class of IFP have been detected in normal ocular tissues. The external epithelia exhibit complex expression patterns of cytokeratin (CK) polypeptides, with CK3 and CK12 being specific markers of the corneal epithelium. Recent research has revealed that single mutant CK polypeptides may play a role in the pathogenesis of corneal dystrophies. The internal ocular epithelia reveal simple but specific patterns of IFP expression, these comprising simple-epithelial CKs and/or the mesenchymal IFP, vimentin. The IFP complement of the neuronal structures of the eye embraces several distinct IFP classes and reflects the diversity of the cell types present at these sites. With respect to ocular tumors, the IFP profile of melanomas might be correlated with metastatic potential. In conclusion, IFP analysis may be able to cast light on the pathogenesis of ocular diseases, as well as being a valuable adjunct in ophthalmopathological diagnosis.

The exact expression of glial fibrillary acidic protein (GFAP) in trigeminal ganglion and dental pulp

The expression in various cell types of peripheral tissues of glial fibrillary acidic protein (GFAP), first discovered as an intermediate filament specific for astrocytes, remains controversial owing to numerous reports of a wide distribution for GFAP-immunoreactivity in various cells. The present study employed immunohistochemistry to investigate the precise expression of GFAP in the dental pulp and trigeminal ganglion of adult rats and wild-type mice as well as GFAP-knockout mice. The exhibition of GFAP-immunoreactivity in the trigeminal ganglion was further examined by a reverse transcription polymerase chain reaction (RT-PCR) technique, and in situ hybridization histochemistry using a specific cRNA probe prepared by us. The immunoreaction for GFAP was recognizable in the axons, Schwann cells, and the fibroblasts in the dental pulp of rats and wild-type littermate mice. However, mice with null mutations in the GFAP gene remained immunoreactive for GFAP in all these locations. Intense GFAP-immunoreactivity was found in a small number of satellite cells in the trigeminal ganglion in all animals examined in this study. RT-PCR analysis demonstrated bands for the GFAP gene corresponding to the length expected from the primer design in the samples of trigeminal ganglion and dental pulp. In situ hybridization histochemistry also showed intense signals for GFAP mRNA in some satellite cells of the trigeminal ganglion, but never in the neurons. These data suggest that the GFAP-immunoreactive molecules in the pulpal axons and fibroblasts react non-specifically with the polyclonal antibody and are probably a closely related type of intermediate filament.

Drebrin particles: components in the ensemble of proteins regulating actin dynamics of lamellipodia and filopodia

Drebrin, an actin-binding 70-kDa protein with an unusually slow SDS-PAGE mobility corresponding to approximately 120 kDa, containing a proline-rich, profilin-binding motif, had originally been reported from neuronal cells, but recently has also been found in diverse other kinds of tissues and cell lines. In biochemical analyses of various cells and tissues, employing gel filtration, sucrose gradient centrifugation, immunoprecipitation and -blotting, we have identified distinct states of soluble drebrin: a approximately 4S monomer, an 8S, ca. 217-kDa putative trimer, a 13S and a > 20S oligomer. In the 8S particles only [35S]methionine-labelled drebrin but no other actin-binding protein has been detected in stoichiometric amounts. By immunofluorescence and immunoelectron microscopy, drebrin-positive material often appeared as "granules" up to 400 nm in diameter, in some cell types clustered near the Golgi apparatus or in lamellipodia, particularly at leading edges, or in dense-packed submembranous masses at tips (acropodia) or ruffles of leading edges, in filopodia and at plaques of adhering junctions. We conclude that these drebrin complexes and drebrin-rich structures allow the build-up and maintenance of high local drebrin concentrations in strategic positions for the regulation of actin filament assembly, thereby contributing to cell motility and morphology, in particular local changes of plasticity and the formation of protrusions.

Immunohistochemical and ultrastructural study of ito cells (fat-storing cells) in response to extrahepatic bile duct ligation in broiler chickens

The Ito cell (fat-storing cell) lies in perisinusoidal space of liver and has a variety of functions. We investigated the immunohistochemistry and ultrastructure of Ito cells in normal and cholestatic livers of broiler chickens. Immunohistochemistry demonstrated that Ito cells expressed HHF35 muscle actin, vimentin, desmin, glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), chromogranin A and cytokeratins in normal livers. These cells were diffusely scattered throughout the lobules. Livers treated with extrahepatic bile duct ligation (BDL) showed cholestasis, fibrosis, proliferation of biliary ductules and Ito cells. The Ito cells were frequently found in fibrotic areas and were larger in size with more extensive immunoreactivity than those of normal livers. Ultrastructural study demonstrated that Ito cells were closely associated with the production of collagen fibers in BDL livers. These findings suggest that Ito cells actively react against hepatocytic injuries and play a major role in the hepatic fibrogenesis of cholestatic livers of chickens.

GFAP is expressed as a major soluble pool associated with glucagon secretory granules in A-cells of mouse pancreas

To elucidate the role of intermediate filament proteins in endocrine cells, we investigated the expression and subcellular distribution of GFAP in mouse islets of Langerhans. For this purpose, combined immunocytochemical and biochemical analysis with a panel of antibodies was carried out to identify GFAP-immunoreactive cells in mouse endocrine pancreas. Cell fractionation into NP-40-soluble and detergent/high salt-insoluble components was performed to assess whether GFAP was located in the cytosolic and/or cytoskeletal compartments of immunoreactive cells. Immunoelectron microscopic analysis was carried out to determine the subcellular distribution of the protein. Peripheral islet cells were stained with anti-GFAP antiserum. These cells were identified as glucagon-secreting cells by immunocytochemical staining of consecutive sections with anti-somatostatin, anti-GFAP, and anti-glucagon antisera. Western blotting analysis of both NP-40-soluble and detergent/high-salt insoluble fractions of isolated islets of Langerhans allowed detection of GFAP in both cytosolic and cytoskeletal compartments. Interestingly, however, the former location was highly predominant. In addition, immunoelectron microscopy localized GFAP associated with the periphery of secretory granules. On the basis of these results, an intriguing role for GFAP in secretory events should be strongly suspected.(J Histochem Cytochem 48:1233-1242, 2000)

Aberrant expression of a cytokeratin in a subset of hepatocytes during chronic WHV infection

Chronic infection of woodchucks with woodchuck hepatitis virus (WHV) invariably leads, within 2-4 years, to the appearance of hepatocellular carcinoma (HCC). HCC is preceded by an extended period of chronic liver damage, probably resulting from the immune response to viral antigens. It may be that infection itself also induces changes in the hepatocyte population. To begin to identify some of the changes in the liver prior to the appearance of HCC, monoclonal antibodies (MAbs) were generated from mice immunized with hepatocytes from a woodchuck chronically infected with WHV or with a tumor lysate. Immunofluorescence microscopy was used to select MAbs that reacted with host markers whose patterns of expression would distinguish chronically infected from uninfected liver or from liver tumors. One of these MAbs (2F2) reacted strongly with a subset of hepatocytes in chronically infected liver; a similar staining pattern was not detected in uninfected or transiently infected liver. Evidence is presented that this strong staining reaction reflects the overexpression or accumulation of the hepatocyte-specific intermediate filament protein, cytokeratin K18, a protein previously implicated in cryptogenic cirrhosis of the liver in humans (Ku, N. O. , Wright, T. L., Terrault, N. A., Gish, R., and Omary, M. B. J. Clin. Invest. 99: 19-23, 1997). Double immunofluorescent staining with antibodies to K18 and M-envelope protein of WHV suggested that strong reactivity to K18 was limited to cells expressing high levels of one or both of the large viral-envelope proteins, M and L; however, high expression of these viral proteins was not always associated with a strong K18 staining reaction.

Structure, development and function of cytoskeletal elements in non-neuronal cells of the human eye

The cytoskeleton, of which the main components in the human eye are actin microfilaments, intermediate filaments and microtubules with their associated proteins, is essential for the normal growth, maturation, differentiation, integrity and function of its cells. These components interact with intra- and extracellular environment and each other, and their profile frequently changes during development, according to physiologic demands, and in various diseases. The ocular cytoskeleton is unique in many ways. A special pair of cytokeratins, CK 3 and 12, has apparently evolved only for the purposes of the corneal epithelium. However, other cytokeratins such as CK 4, 5, 14, and 19 are also important for the normal ocular surface epithelia, and other types may be acquired in keratinizing diseases. The intraocular tissues, which have a relatively simple cytoskeleton consisting mainly of vimentin and simple epithelial CK 8 and 18, differ in many details from extraocular ones. The iris and lens epithelium characteristically lack cytokeratins in adults, and the intraocular muscles all have a cytoskeletal profile of their own. The dilator of the iris contains vimentin, desmin and cytokeratins, being an example of triple intermediate filament expression, but the ciliary muscle lacks cytokeratin and the sphincter of the iris is devoid even of vimentin. Conversion from extraocular-type cytoskeletal profile occurs during fetal life. It seems that posttranslational modification of cytokeratins in the eye may also differ from that of extraocular tissues. So far, it has not been possible to reconcile the cytoskeletal profile of intraocular tissues with their specific functional demands, but many theories have been put forward. Systematic search for cytoskeletal elements has also revealed novel cell populations in the human eye. These include transitional cells of the cornea that may represent stem cells on migration, myofibroblasts of the scleral spur and juxtacanalicular tissue that may modulate aqueous outflow, and subepithelial matrix cells of the ciliary body and myofibroblasts of the choroid that may both participate in accommodation. In contrast to the structure and development of the ocular cytoskeleton, changes that take place in ocular disease have not been analysed systematically. Nevertheless, potentially meaningful changes have already been observed in corneal dystrophies (Meesmann's dystrophy, posterior polymorphous dystrophy and iridocorneal endothelial syndrome), degenerations (pterygium) and inflammatory diseases (Pseudomonas keratitis), in opacification of the lens (anterior subcapsular and secondary cataract), in diseases characterized by proliferation of the retinal pigment epithelium (macular degeneration and proliferative vitreoretinopathy), and in intraocular tumours (uveal melanoma). In particular, upregulation of alpha-smooth muscle actin seems to be a relatively general response typical of spreading and migrating corneal stromal and lens epithelial cells, trabecular cells and retinal pigment epithelial cells.

Cell types of secondary cataract: an immunohistochemical analysis with antibodies to cytoskeletal elements and macrophages

BACKGROUND

The study was carried out to identify cell types of secondary cataract after extracapsular cataract extraction and implantation of an intraocular lens.

METHODS

Twenty-five formalin-fixed, paraffin-embedded pseudophakic human eyes with secondary cataract, obtained at autopsy, were studied and compared to a specimen from an anterior subcapsular cataract with a panel of six monoclonal antibodies (MAbs, to vimentin, cytokeratin (CK) 8 and 18, desmin, alpha-smooth muscle actin, and the CD68 epitope of macrophages by the avidin-biotinylated peroxidase complex (ABC) method.

RESULTS

MAb Vim 3B4 to vimentin immunolabeled spindle-shaped cells in 16 of 17 central plaques of secondary cataract as well as cells in all 16 Soemmering's ring cataracts. Spindle-shaped cells reacted with MAb CAM 5.2 to CK 8 in 13 of 18 eyes, but only one specimen was labeled with MAb CY-90 to CK 18. No immunoreaction was seen with MAb D33 to desmin, whereas MAb 1A4 to alpha-smooth muscle actin immunolabeled spindle-shaped cells in 15 of 18 plaques of secondary cataract. Macrophages were seen with MAb PG-M1 in 13 of 19 secondary cataracts. In the anterior subcapsular cataract, spindle-shaped cells under a wrinkled but otherwise intact capsule reacted with MAb Vim 3B4 to vimentin, MAb CAM 5.2 to CK 8, and MAb 1A4 to alpha-smooth muscle actin.

CONCLUSION

Spindle-shaped cells in secondary and anterior subcapsular cataracts react with antibodies to vimentin, CK 8 and alpha-smooth muscle actin, suggesting them to be metaplastic epithelial cells that derive from the lens epithelium. alpha-Smooth muscle actin persists in them at least 10 years postoperatively, but CK 8 starts to disappear after 3 years. Macrophages are one possible modulator of this transdifferentiation.

Identification and localization of a neurally expressed member of the plakoglobin/armadillo multigene family

The plakoglobin/armadillo multigene family comprises many proteins widely differing in sizes and functions which have in common a variable number of tandemly repeated arm sequences of about 42 amino acids (aa). In a search for proteins with sequence homology to the desmosomal-plaque-associated arm-repeat-containing protein, plakophilin 1, we have identified a novel plakoglobin/armadillo protein. This new member of the multigene family is predominantly, if not exclusively, expressed in neural and neuroendocrine tissues, hence the name neural plakophilin-related arm-repeat protein (NPRAP). The murine cDNA codes for a protein of 1247 aa, with a predicted molecular weight of 135 kDa and a pI of 7.57. The orthologous human protein differs only in a few aa, indicative of the evolutionary stability of NPRAP. In human and murine cDNAs, we have found different transcripts of the NPRAP gene, suggesting that in each species the protein exists in at least two isoforms. The NPRA protein contains three different regions: a 528-aa amino-terminal "head" domain, including a potential coiled-coil-forming alpha-helix segment, a central domain with 10 imperfect arm-repeat units, and a 212-aa carboxy-terminal "tail" domain. By aa sequence, NPRAP is highly homologous to three proteins: p120cas, p0071 and ARVCP, which represent a distinct subgroup within the plakoglobin/armadillo family. By in situ hybridization and immunofluorescence microscopy using NPRAP-specific antibodies, we have demonstrated NPRAP and its mRNA in the perikarya of various kinds of CNS neurons in embryonic and adult mice, but minimal amounts have also been detected by immunoblot analysis in some other tissues containing neural or neuroendocrine elements. We have not seen significant enrichment of NPRAP at cell junctions or in nuclei. Possible NPRAP functions are discussed and the correlation of NPRAP synthesis with neuronal differentiation processes is emphasized.

Intermediate filaments in the nervous system: implications in cancer

In this review, we describe the different intermediate filament (IF) proteins, their assembly into IFs, the functions of IFs and their relation to disease with a particular emphasis on the intermediate filaments expressed in the nervous system. In the mammalian nervous system, seven intermediate filament proteins are known to be expressed in neurons or neuroblasts. These include the three neurofilament triplet proteins, which are present in both central and peripheral neurons; alpha-internexin, which is the first neuronal intermediate filament protein expressed in the developing mammalian nervous system and present primarily in CNS neurons in the adult nervous system; peripherin, which is most abundant in the PNS; vimentin, which is expressed in neuronal progenitor cells along with nestin, as well as in a few adult neurons. In contrast to these neuron-specific IF proteins, the glial fibrillary acidic protein (GFAP) is glial specific and expressed in mature astrocytes. Vimentin and nestin are also expressed in glial progenitor cells and vimentin is expressed along with GFAP in some mature astrocytes. As a whole, the expression of IF proteins is tissue specific and developmentally regulated. As a result, IF proteins are good markers for determining the cell origin and differentiation status of tumor cells. For example, peripherin is expressed in neuroblastomas, GFAP in astrocytomas and neurofilaments in tumors of neuronal origin. However, tumor cells may express IF patterns which are irrelevant to their cell origin. Therefore, one has to be very careful in using IF patterns as sole indicators of cell origin and differentiation status of tumors.

Plakophilins 2a and 2b: constitutive proteins of dual location in the karyoplasm and the desmosomal plaque

Using antibodies and recombinant DNA techniques, we have identified plakophilin 2, a novel desmosomal plaque protein of M(r) 100,000 (estimated from SDS-PAGE), which is a member of the arm-repeat family of proteins and can occur in two splice forms (2a and 2b) because of the insertion of a 44 amino acid (aa)-encoding exon. In its aa sequence (837 and 881 aa, calculated pIs: 9.33 and 9.38, mol wts 92,750 and 97,410 kD), it is conspicuously related to the 80-kD plakophilin 1, with which it shares a central region of 9 repeats of the arm-motif, preceeded by a long head region and followed by a very short (11 aa) carboxy-terminal sequence. Plakophilin 2 and its mRNA have been detected in a wide range of tissues and cell types, including cells devoid of desmosomes. By light and electron microscopical immunolocalization, plakophilin 2 has been localized to plaques of desmosomes of one-layered ("simple") and complex epithelia, carcinomas, diverse epithelium-derived cell culture lines, as well as cardiac tissue and the dendritic reticulum cells of lymphatic germinal centers, i.e., desmosomes in which plakophilin 1 is not detected. However, plakophilin 2 has also been localized in the desmosomes of certain but not all stratified epithelia where it coexists with plakophilin 1. Remarkably, plakophilin 2 is also enriched in the karyoplasm of a wide range of cell types, including many that lack desmosomes and in which, therefore, the nuclear state is the only locally enriched form of plakophilin 2 present. We conclude that plakophilins 2a and 2b are basic nuclear proteins that in certain cell types additionally assemble with other proteins to form the desmosomal plaque and serve general nuclear functions as well as a function specific to many but not all desmosomes.

Symplekin, a novel type of tight junction plaque protein

Using a monoclonal antibody we have identified and cDNA-cloned a novel type of protein localized, by light and electron microscopy, to the plaque associated with the cytoplasmic face of the tight junction-containing zone (zonula occludens) of polar epithelial cells and of Sertoli cells of testis, but absent from the junctions of vascular endothelia. The approximately 3.7-kb mRNA encodes a polypeptide of 1142 amino acids (calculated molecular weight 126.5 kD, pI 6.25), for which the name "symplekin" (from Greek sigma upsilon mu pi lambda epsilon kappa epsilon iota, nu, to tie together, to weave, to be intertwined) is proposed. However, both the mRNA and the protein can also be detected in a wide range of cell types that do not form tight junctions or are even completely devoid of any stable cell contacts. Careful analyses have revealed that the protein occurs in all these diverse cells in the nucleoplasm, and only in those cells forming tight junctions is it recruited, partly but specifically, to the plaque structure of the zonula occludens. We discuss symplekin as a representative of a group of dual residence proteins which occur and probably function in the nucleus as well as in the plaques exclusive for either tight junctions, adherens junctions, or desmosomes.

Glial fibrillary acidic protein--a cell type specific marker for Ito cells in vivo and in vitro

BACKGROUND/AIMS

Glial fibrillary acidic protein is an intermediate filament first identified in the brain in astrocytes. This study examines glial fibrillary acidic protein immunoreactivity in normal and damaged rat livers. Glial fibrillary acidic protein-gene-expression in Ito cells, endothelial cells, Kupffer cells, and hepatocytes is also analyzed.

METHODS

Sequential cryostat sections from normal, as well as acutely or chronically CC14 damaged rat livers were analyzed by immunostaining for the presence of glial fibrillary acidic protein and desmin. Glial fibrillary acidic protein-expression in isolated liver cells was studied by immunocytology, Western blot, Northern blot analysis, and reverse-transcription polymerase chain reaction. The specificity of polymerase chain reaction products was tested by Southern blot hybridization and partial sequencing.

RESULTS

In the normal liver, glial fibrillary acidic protein-positive cells were detected in the perisinusoidal area. These cells were also desmin-immunoreactive as determined by immunostaining. In contrast, cells of the vessel walls were desmin-positive, but glial fibrillary acidic protein-negative. In the acutely damaged livers glial fibrillary acidic protein-positivity was detectable along the non-damaged sinusoids as well as in the necrotic areas. In chronically damaged livers glial fibrillary acidic protein was more detectable at the margins of the fibrotic septa, less inside the septa. All glial fibrillary acidic protein-positive cells were desmin-positive, but several desmin-positive cells were glial fibrillary acidic protein-negative (especially inside the septa). Among the different liver cell subpopulations tested in vitro, glial fibrillary acidic protein-gene expression was only detectable in Ito cells. During primary culture, glial fibrillary acidic protein-expression decreased in parallel to Ito cell activation.

CONCLUSIONS

Glial fibrillary acidic protein is a new cell type specific marker for Ito cells, which might allow distinction between Ito cells and other fibroblastic liver cells (cells of the vessel walls). Cells located at the margins of fibrotic septa definitely represent Ito cells.

Gastric schwannoma--a clinicopathological analysis of six cases

Six gastric schwannomas found among 150 mesenchymal tumours of the gastrointestinal tract were analysed clinically, histologically and immunohistochemically. These tumours occurred in the wall of stomach in middle-aged patients, five women and one man, and measured 2-9 cm in diameter. Follow-up from 3 to 24 years showed no recurrences or metastases. Histologically, all tumours were composed of spindle cells with vague nuclear palisading and variably myxoid stroma. One case showed a multinodular pattern of growth, reminiscent of plexiform neurofibroma. In all cases, there was a peripheral cuff-like B-lymphocyte infiltration with germinal centers in two cases. None of the tumours showed mitotic activity. Immunohistochemically, the tumour cells were positive for S-100 protein and focally for GFAP and CD57 (Leu 7). They were negative for desmin and actin, unlike true leiomyomas, and negative for CD34, unlike most gastrointestinal stromal tumours that were examined for comparison. Electronmicroscopy of three cases showed complex cell processes surrounded by prominent basement membranes, while myofilaments were not present. These cases show that schwannomas can be identified as rare, benign gastrointestinal tumours which probably arise from the gastrointestinal autonomic nervous system.

Benign and malignant salivary gland-type mixed tumors of the lung. Clinicopathologic and immunohistochemical study of eight cases

BACKGROUND

Primary lung tumors showing features of salivary gland-type neoplasms are extremely rare.

METHODS

Eight patients with primary lung neoplasms showing light microscopic and immunohistochemical features of salivary gland-type mixed tumors were studied.

RESULTS

The patients were six women and two men, ages 35-69 years (mean, 52.5 years). The tumors ranged from 2 to 16 cm in greatest diameter. In two patients the lesions presented as polypoid endobronchial lesions obstructing the lumen; in another two patients the lesions were found in close proximity or in continuity with a bronchus; in three patients, the lesions presented as peripheral parenchymatous nodules unrelated to a bronchus; and in one patient, the relationship to the bronchus could not be determined. Histologically, the lesions were biphasic, showing admixtures in varying proportions of epithelial elements containing a predominant myoepithelial cell population with a stromal component containing an abundant myxoid or focally chondroid matrix. Immunohistochemical studies showed strong positivity of the cells in the epithelial component with low molecular weight keratins (CAM 5.2), and to a lesser extent with broad spectrum keratin, actin, and vimentin antibodies. The cells also showed variable reactivity in the epithelial and nonepithelial elements with S-100 protein and glial fibrillary acidic protein. Six tumors were grossly and histologically benign; in two patients, the tumors were larger, locally invasive, and showed more atypical histologic features. All patients were treated with surgical excision. On follow-up, of the six patients with histologically benign-appearing tumors, one was alive and well 6 years after surgery; another died 4 years after surgery of a second unrelated malignancy; one died during the immediate postoperative period of myocardial infarction; and three have been lost to follow-up. In the two patients with histologically atypical lesions, the tumors recurred and metastasized after 2 and 3 years, respectively, with one of them leading to death caused by widespread metastases and superior vena cava syndrome.

CONCLUSIONS

Review of the literature and the findings in the current series indicate that salivary gland-type mixed tumors of the lung may present with a spectrum of histologic features and clinical behavior, ranging from benign to frankly malignant, similar to that observed for their salivary gland counterparts. Size of the lesion at the time of presentation, extent of local infiltration, and degree of mitotic activity appear to be the most reliable prognostic features of these tumors.

Pathology of the salivary glands: the contribution of electron microscopy

Electron microscopy has a limited role in the diagnosis of primary salivary gland tumors, although it can be helpful in metastatic lesions of possible salivary gland origin. The diversity of subtypes in salivary gland tumors, as well as the range of histomorphology within any one subtype, is unparalleled in any other human tumor. This and their relative infrequency causes diagnostic problems for pathologists. Ultrastructural techniques have been of major importance in determining the inter-relationship of these tumors for classification purposes, revealing the subtle variations in common cellular differentiation pathways, determining the organization of tumor cells, and displaying the importance of extracellular matrix materials in establishing diagnostic criteria for each of the many subtypes. Electron microscopy has also been valuable in non-neoplastic salivary gland disease and has an increasing role in experimental studies involving tissue from human and animal salivary parenchyma.

Immunohistochemistry in tumour diagnosis

Immunohistochemistry has become an everyday tool in diagnostic pathology to increase the accuracy in tumour typing. The most important recent developments include availability of antibodies to leukocyte CD-antigens to nearly comprehensive lymphoma typing in paraffin sections, use of certain leukocyte antigens in typing of solid tumours, e.g. neoplastic endothelial cells (CD31 and CD34) and neural and neuroendocrine cells (CD56, CD57). Also, antibodies selective to individual keratin polypeptides promise to be helpful in the subtyping of carcinomas. Antibodies to nuclear proliferation antigens have already proven helpful in the characterization of tumour cell proliferation. Technical optimization, using enzymatic and non-enzymatic antigen retrieval modalities, is also important.

Folliculo-stellate cells in the human anterior pituitary express cytokeratin

Recent studies have suggested that the anterior pituitary is derived not from Rathke's pouch, but instead from neuroectoderm. To address this controversy and the differentiation of the adenohypophysis, we evaluated folliculo-stellate cells from 7 human pituitaries using a panel of immunohistochemical stains. The panel included antibodies to a low molecular weight cytokeratin (CK-8), a broad spectrum of cytokeratins (AE 1/AE 3), S-100 protein, vimentin, and glial fibrillary acid protein. The most intense immunostaining was observed with the antibody to broad spectrum cytokeratins. Less intense immunohistochemical staining of folliculo-stellate cells was observed with the antibodies against glial fibrillary acidic protein and S-100 protein. Immunoblotting of anterior pituitary tissue obtained from 3 autopsied patients showed that cytokeratins identified in the anterior pituitary were of low molecular weight (40 to 56 Kd). These results indicate that folliculo-stellate cells show epithelial differentiation, and support the hypothesis that the anterior pituitary is derived from Rathke's pouch.

Atypical lung carcinoid with GFAP immunoreactive cells

A case of atypical carcinoid with peculiar histological and ultrastructural pattern and immunohistochemical phenotype is presented. The neoplasm is composed of three types of cells. Type 1 cells are small to medium sized, fusiform, with scarce cytoplasm and are arranged in fascicles. Type 2 cells are cuboidal and line acinar structures. Type 3 cells have more abundant eosinophilic cytoplasm, larger nuclei and are arranged in fascicles intersecting with fascicles of type 1 cells, and sometimes surround acinar structures. The three cell types are present both in the primary lesion and in its lymph node metastases. Immunohistochemistry demonstrates immunoreactivity of all cell types for general neuroendocrine markers. Cytokeratin immunoreactivity is more prominent in type 1 and 2 cells, and is only focally expressed in type 3 cells. Type 3 cells are also immunoreactive for glial fibrillary acidic protein (GFAP), alpha-actin, S-100 protein, vimentin. Electron microscopic examination confirms the neuroendocrine nature of the cells, and show that type 3 cells have prominent bundles of intermediate filaments, electron-dense granules and junctional complexes. To our knowledge, this is the first case of atypical lung carcinoid with GFAP immunoreactivity. The nature of type 3 GFAP positive cells is unclear. There are some clues pointing to their sustentacular nature, and other ones pointing to a myoepithelial origin, but the data are inconclusive. Type 3 cells may be the malignant counterpart of sustentacular cells seen in typical carcinoids, but their GFAP positivity and the presence of electron-dense granules are very unique features, which differentiates them from sustentacular cells. Alternatively, their unusual GFAP + immunohistochemical phenotype may be due to aberrant expression of cytoskeletal proteins.

Cloning of a type I keratin from goldfish optic nerve: differential expression of keratins during regeneration

We report the cDNA sequence and predicted amino acid sequence of a novel type I keratin, designated as GK50, and show that keratin expression in the goldfish optic nerve is highly complex. The GK50 protein is one of at least three type I keratins expressed in goldfish optic nerve based on both antibody reactivity and blot-binding to the type II keratin ON3. After optic nerve crush in situ hybridization shows a localized increase in GK50 mRNA expression in the crush zone. This is in contrast to ON3 mRNA which shows a localized increase that is limited to the proximal and distal margins of the crush zone, suggesting a diversity of keratin expression in different cell types of the goldfish optic nerve.

Osteogenic sarcoma with epithelial differentiation

This case report details an osteogenic sarcoma arising in a vertebra in which cytokeratin intermediate filaments were detected immunohistochemically with three different antibodies. This feature was present not only in the primary neoplasm but also in two local recurrences and a metastasis to the iliac bone. What is unique about this primary bone tumor, however, is the structural evidence for epithelial differentiation. Ultrastructurally, well-formed desmosomes and tonofilaments were present in all four surgically resected specimens. This tumor expands the list of soft tissue and bone tumors in which anomalous expression of intermediate filaments can occur but, more important, illustrates that changes in genetic expression of neoplasia of mesenchymal origin can result in paradoxic epithelial differentiation.

Changes of expression of intermediate filament proteins during ontogenesis of eccrine sweat glands

The intermediate filament expression in fetal and adult human eccrine sweat glands was studied by immunoperoxidase microscopy performed on cryostat sections using monoclonal antibodies against various cytokeratins (CK), vimentin, and actin. In palmar skin of 14-week-old fetuses, the early dermal cords showed a primitive CK pattern similar to that of epidermal basal cells. From week 15 on (distal finger skin), inner cells of the proximal (ductal) portion of the glandular anlagen expressed CK 1/10/11 and 19 (markers of adult eccrine ductal luminal cells). In addition, CK 4 was expressed in ductal luminal cells mainly in the fetal period. In the distal portion of the sweat gland anlagen the increased or new expression of the simple-epithelium-type CK 7, 8, 18, and 19 was detected at week 15, indicating the onset of the secretory differentiation pathway. Two subsegments of the prospective secretory portion could be distinguished (elongated part and end bud). Interestingly, in fetuses, most secretory portion cells co-expressed vimentin in addition to CK. From week 22 on, peripheral cells of the secretory portion were stained for CK 17 and smooth-muscle-type actin, suggesting myoepithelial differentiation. In newborn and adult eccrine glands, secretory cells expressed mainly CK 7, 8, 18, and 19, whereas myoepithelial cells were conspicuous by their co-expression of certain CK (including CK 5 and 17), vimentin, and smooth-muscle-type actin and sometimes even glial filament protein (GFP), similar to myoepithelial cells of other glands. These results throw further light onto the complex processes of fetal development of eccrine sweat glands and their cellular diversification. The possible biologic significance of the differential CK expression in the various glandular cell types is discussed.

Immunohistochemical and ultrastructural correlates of muscle-actin expression in pleomorphic adenomas and myoepitheliomas based on comparison of formalin and methanol fixation

The degree and range of differentiation of the cells referred to as myoepithelial-like in pleomorphic adenomas and the tumour cells of myoepitheliomas are not definitely established. This type of information is critical for establishing reliable diagnostic criteria, such as expression of muscle-specific actin and ultrastructural identification of myofilaments, in these and other salivary gland tumours. Pleomorphic adenomas (18) and myoepitheliomas (5), of which 10 cases were fixed only in formalin and 13 cases where tissues were fixed in both formalin and methanol/acetic acid, were studied. Each tumour and normal accompanying parotid was immunostained with two monoclonal antibodies for smooth muscle actin, HHF35 and MSA. Staining of myoepithelial cells was absent in certain samples of normal gland with both HHF35 (15%) and MSA (69%) when formalin-fixed tissue was used. Using formalin-fixed tissue from 15 pleomorphic adenomas/myoepitheliomas, 2 (14%) had focal positivity with HHF35, while 8 cases (57%) were positive with MSA. However, a certain degree of false positivity was suspected since in samples of normal parotid, both acinar and duct cells were frequently stained, particularly with MSA. With methanol/acetic acid-fixed tissue only 4 of 13 cases (31%) were positive with either MSA or HHF35 and 2 of these only had a minor proportion of the tumour cells expressing muscle-specific actin. Using alcohol-fixed tissue, myoepithelial cells were strongly stained in all examples of normal parotid gland with both anti-actin antibodies. In 5 cases examined by electron microscopy, there was no apparent correlation between immunohistochemical results and the presence or absence of cytoplasmic filament accumulation. The results indicate considerable tumour cell heterogeneity in muscle-specific actin expression and suggest that non-luminal cells in pleomorphic adenomas and the tumour cells in myoepitheliomas may differentiate as classical myoepithelial cells, as partially differentiated (i.e. modified myoepithelial cells) or as the counterpart of basal cells present in the intra- and interlobular ducts of normal salivary gland.

Expression of oligodendroglia and Schwann cell markers in human nervous system tumors. An immunomorphological study and western blot analysis

Sixty tumors of the central and peripheral nervous system and seven brain metastases of extracranial carcinomas were examined using the peroxidase-antiperoxidase method to study the expression of myelin basic protein (MBP), myelin-associated glycoprotein (MAG) and the HNK-1/Leu-7 epitope. The immunocytochemical findings were compared with and correlated to Western blot results. None of the tumor types, including oligodendrogliomas, neurinomas and neurofibromas, expressed MAG and MBP, whereas myelin sheaths and their remnants within the tumors yielded specific immunoreactions. In contrast, the HNK-1/Leu-7 antibodies labelled the majority of the tumors tested including oligodendrogliomas and Schwann cell tumors. As demonstrated by Western blot experiments the HNK-1/anti-Leu-7 antibodies exhibited positive reactions with diverse polypeptides both in tumors and in non-neoplastic brain tissue at positions not corresponding to MAG. This suggests that the epitope recognized by HNK-1/Leu-7 antibodies is shared by a variety of unrelated proteins in normal and neoplastic tissues. Our results strongly indicate the absence of detectable amounts of MBP and MAG in oligodendrogliomas and Schwann cell tumors. The immunomorphological and immunochemical findings clearly showed the wide distribution of the HNK-1 epitope within different tumor types of the central and peripheral nervous system. In conclusion, the data demonstrate that specific cell markers for human oligodendrogliomas and Schwann cell tumors are still lacking.

Glial fibrillary acidic protein immunoreactivity in adrenocortical and Leydig cells of the Syrian golden hamster (Mesocricetus auratus)

In an immunocytochemical investigation of the expression of glial fibrillary acidic protein (GFAP) in non-nervous system tissues ten anti-GFAP antibodies were used on a range of normal adult organs from different species. All four polyclonal and six monoclonal antibodies revealed the expression of GFAP in cells of the zona fasciculata and reticularis of the adrenal cortex and Leydig cells of the Syrian hamster. The Chinese hamster, mole, rat, mouse, guinea pig, rabbit, pig, duck and man were negative. Co-expression of immunoreactivity for GFAP and vimentin was observed in adrenocortical and Leydig cells of the Syrian hamster but there were differences in the staining patterns of these intermediate filament proteins. Expression of GFAP in adrenal cortex of Syrian hamster is confirmed by immunoblot and limited proteolysis analysis which reveal a light form which is immunochemically indistinguishable from its counterpart in the central nervous system. The results presented here suggest a new model for the study of the possible role of GFAP expression in cells known to be sites of steroid synthesis.

Pleomorphic adenoma of the breast: a clinicopathologic and immunohistochemical study of 10 cases

Pleomorphic adenomas of the breast (PAB) are uncommon tumors. We studied the clinicopathologic features of 10 cases of PAB, seven of which were assessed immunohistochemically. Nine patients were women, with a median age at diagnosis of 65 years. Eight patients presented with a palpable mass; two had a nipple discharge. Nine of the tumors were periareolar. The latter epidemiologic findings, coupled with histologic observations, appeared to indicate a preferential origin for PAB within large intramammary ducts. These neoplasms histologically resemble their analogues in salivary glands. Moreover, a gradual histologic transition between different morphologic areas in PAB, especially between mesenchymal and epithelial regions, supported the contention that the neoplasm arises from a single cell type capable of divergent differentiation and thus should not be considered a "mixed" tumor. This contention was further substantiated by immunohistochemical findings, in which three intermediate filaments (cytokeratin, vimentin, and glial fibrillary acidic protein) and muscle-specific actin were expressed conjointly in tumor cells with a variety of morphologic appearances. In addition, cells differentiating along mesenchymal lines by conventional microscopy were found to express epithelial membrane antigen or gross cystic disease fluid protein-15 in five cases. The benign nature of PAB was supported by a lack of metastases in this series during a median follow-up period of 4.9 years. However, one lesion recurred locally. Regarding therapy, we believe that PAB can be excised successfully with only a narrow circumferential margin of uninvolved breast.

Complexity of expression of intermediate filament proteins, including glial filament protein, in endometrial and ovarian adenocarcinomas

The expression patterns of intermediate filament proteins of primary and metastatic endometrial (n = 18) and ovarian (n = 24) adenocarcinomas were analyzed by immunocytochemistry using a panel of specific antibodies and by gel electrophoresis of cytoskeletal preparations, followed by immunoblotting. All cells of all endometrial adenocarcinomas studied contained the "simple epithelial"-type cytokeratins (CKs) 8, 18, and (mostly) 19, with variable numbers of cells also positive for CK 7 and vimentin. In addition, most of these tumors contained individual cells or groups of cells that were positive for the stratification-related CKs 4, 5, 6, 13, 14, and 17. The latter CKs were often associated with squamous cell foci, but were also found in some single (nonsquamous) tumor cells, indicative of early stages of squamous cell differentiation. Ovarian carcinomas of various histologic types and grades contained predominantly CKs 7, 8, 18, and 19. Serous, endometrioid, and anaplastic tumors, but not mucinous and clear cell tumors, also contained minor amounts of stratification-related CKs in variable combinations, mostly including CK 4. In all tumor types except mucinous tumors, vimentin was consistently detected in variable proportions of tumor cells which, however, were rather low in anaplastic carcinomas. Surprisingly, glial filament protein was detected in a minor proportion (< or = 20%) of tumor cells in seven of 14 serous and endometrioid ovarian carcinomas and in three of 18 endometrial carcinomas. These different intermediate filament expression patterns of müllerian duct-type carcinomas, only partly related to the morphologic appearance of the specific type of tumor, might reflect the multipotentiality of differentiation of müllerian duct-derived epithelia. Cytoskeletal features of potential diagnostic value, especially in metastatic carcinomas, are discussed.

Glial fibrillary acidic protein immunoreactivity in normal and diseased human breast

Immunostaining for glial fibrillary acidic protein (GFAP) identifies a minor subpopulation of immunoreactive myoepithelial cells in the normal resting human breast. The GFAP-immunoreactive cells also express a panel of myoepithelial cell markers, including cytokeratin 14 (CK 14), vimentin, smooth-muscle-specific actin isoforms, nerve growth factor receptor (NGFR) and common acute lymphoblastic leukaemia antigen (CALLA). The percentage of GFAP-immunoreactive myoepithelial cells is greatly increased in various neoplastic and non-neoplastic diseases of the breast, being highest in adenomyoepitheliomas. Furthermore, in all the instances of fibroadenoma, phyllodes tumour, epitheliosis and gynaecomastia, a variable number of epithelial cells also acquires immunoreactivity for GFAP, vimentin, CK 14, NGFR and, to a lesser extent, for CALLA. Conversely, GFAP immunoreactivity has never been encountered in the malignant cells of the different types of breast carcinoma. These findings suggest that the expression of GFAP might be a (possibly transient) feature of proliferating epithelial and myoepithelial cells in breast diseases other than carcinomas.

Cytokeratins, smooth muscle actin and vimentin in human normal salivary gland and pleomorphic adenomas. Immunohistochemical studies with particular reference to myoepithelial and basal cells

The distribution of immunostaining in normal major salivary gland and in 12 pleomorphic adenomas was studied using monospecific monoclonal antibodies to a number of cytokeratins, including cytokeratin 14, to smooth muscle actin and vimentin. A number of these antibodies enabled a distinction to be made between structural components of the normal gland, and to relate this to the different structures of pleomorphic adenomas. In the normal gland, the luminal duct cells expressed cytokeratins 7, 8, 18 and 19. Three antibodies were of particular value for the characterization of normal myoepithelial and basal cells; while the antibody to smooth muscle actin and the cytokeratin antibody Ks8.12 mutually exclusively stained the myoepithelial (basket) cells and the basal duct (light) cells, respectively, the recently established monospecific antibodies to cytokeratin 14 showed specific immunostaining with both cell types. These three antibodies left luminal cells virtually unstained. Ck 13 was found occasionally in single luminal excretory duct cells. Antibodies to cytokeratins 1/2, 10 and 10/11 did not show any staining in the normal gland. In the pleomorphic adenomas, the staining pattern of the two-layered tubular formation resembled that of the normal gland ducts: tumour luminal cells showed the characteristic, although more irregular, expression of cytokeratins 7, 8, 18 and 19; the outer cells resembled normal ductal basal cells with their anti-cytokeratin 14/Ks8.12-epitope staining and in that they virtually lacked staining for smooth muscle actin. Trabecular formations and cells in myxoid areas were reactive with Ks8.12 and for cytokeratin 14, occasionally also for cytokeratins 7, 18 and 19. Epidermoid cell islets expressed mainly cytokeratin 14 and inconsistently the squamous epithelial cytokeratin 13 and the epidermal cytokeratin 10/11. Vimentin was found in cells of myxoid areas. The results support the postulate that some of the normal duct basal cells act as reserve cells and can give rise to tumour formation with a primitive myxoid or trabecular pattern and a more differentiated tubular or epidermoid configuration.

Immunohistochemical features of giant cell carcinoma of the lung: patterns of expression of cytokeratins, vimentin, and the mucinous glycoprotein recognized by monoclonal antibody A-80

Giant cell carcinoma of the lung (GCCL) is an uncommon and extremely aggressive variant of lung cancer. Characteristic microscopic findings include marked pleomorphism, aggregates of mononucleated or multinucleated giant cells (or both), a general lack of architectural cohesiveness, extensive necrosis, and endocytosis by the giant cells. Although the epithelial character of GCCL has been confirmed by a number of studies, controversy persists as to whether it represents a variant of poorly differentiated adenocarcinoma or of squamous carcinoma. Histochemical studies for mucosubstances have yielded variable and conflicting results. This report describes conventionally fixed and processed samples from 10 cases of GCCL studied with a panel of monoclonal antibodies (Mabs) recognizing different cytokeratin polypeptides (AE1, AE3, AE1/AE3 cocktail, and CAM 5.2), vimentin, and Mab A-80, the last of which binds to a mucinous glycoprotein associated with exocrine differentiation. All 10 cases of GCCL reacted with all cytokeratin Mabs; the extent and intensity of the reaction varied notably. All cases stained strongly and diffusely with Mab AE1 and AE1/AE3, the reaction was less extensive and weaker with CAM 5.2. Significantly, 2 cases reacted focally with Mab AE3. Nine cases reacted extensively and intensely with the vimentin Mab, often showing prominent paranuclear globular profiles. All cases reacted with Mab A-80; the reaction was often strong, but the extent was variable. Findings indicate that all GCCL are indeed cytokeratin positive but that most express polypeptides toward the low-molecular weight end of the spectrum; a small subset also expresses heavier polypeptides.(ABSTRACT TRUNCATED AT 250 WORDS)