High expression of DNA repair pathways is associated with metastasis in melanoma patients

We have identified a gene-profile signature for human primary malignant melanoma associated with metastasis to distant sites and poor prognosis. We analyse the differential gene expression by looking at whole biological pathways rather than individual genes. Among the most significant pathways associated with progression to metastasis, we found the DNA replication (P=10(-14)) and the DNA repair pathways (P=10(-16)). We concentrated our analysis on DNA repair and found that 48 genes of this category, among a list of 234 genes, are associated with metastatic progression. These genes belong essentially to the pathways allowing recovery of stalled replication forks due to spontaneous blockage or induced DNA lesions. Because almost all these differentially expressed repair genes were overexpressed in primary tumors with bad prognosis, we speculate that primary melanoma cells that will metastasize try to replicate in a fast and error-free mode. In contrast to the progression from melanocytes to primary melanoma, genetic stability appears to be necessary for a melanoma cell to give rise to distant metastasis. This overexpression of repair genes explains nicely the extraordinary resistance of metastatic melanoma to chemo- and radio-therapy. Our results may open a new avenue for the discovery of drugs active on human metastatic melanoma.

Protective effect of a brisk tumor infiltrating lymphocyte infiltrate in melanoma: An EORTC melanoma group study

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Background: Tumor-infiltrating lymphocytes (TILs) in melanoma are responsible for tumor killing and may induce spontaneous regression. Brisk TILs in the melanoma vertical growth phase (VGP) is a strong, albeit not independent, prognostic factor associated with superior survival. This study investigated whether more detailed classes of TIL patterns, based on topography and intensity, are independent prognostic factors and identify patients with good prognosis. Methods: The study included 1,171 patients with cutaneous VGP melanoma with at least 3 years of follow up for whom slides were available for review. TIL infiltrate was assessed for pattern (absent, non brisk, brisk), intensity (scanty, moderate, dense), and topography (peripheral, central, both). Pattern was assessed qualitatively: brisk TIL infiltrate was defined as a continuous band of lymphocytes at the base of the melanoma, or throughout the tumor. Other studied variables were: thickness, mitotic count (MC), ulceration, gender, age, anatomic site, melanoma-related death (MRD). Subsequently, Chi-square tests, Kaplan-Meier curves (KM), logrank tests, and Cox models were applied to examine the relation between MRD, TIL categories and interaction with other variables. Results: A brisk infiltrate was observed in 21.2% of the cases. Adjusted hazard ratio for MRD as compared to the absent category was 0.82 (95% CI=0.64–1.06) in the non-brisk category, and 0.43 (95% CI=0.28–0.68) in the brisk category. Based on the Cox model, brisk TIL was an independent prognostic factor for MRD (p<0.001) controlling for thickness, MC, ulceration, gender, age and site. Intensity was significantly associated with MRD for melanomas with peripheral and central brisk TILs (p=0.027) but not for other melanomas. Remarkably, no death was observed in the 5.5% of melanomas with dense, brisk TIL infiltrate at ten years. Conclusions: A brisk TIL pattern was shown to have prognostic value for MRD underscoring the importance of TILs in the outcome of VGP melanoma patients. Furthermore, we identified a small population of “super-responder” patients whose tumor was characterised by a continuous and dense TIL infiltrate and who did not display signs of tumor progression.

No significant financial relationships to disclose.

Chronic radiodermatitis following percutaneous coronary interventions: a report of two cases

We describe two patients in whom chronic radiodermatitis with therapy-resistant ulceration of the right scapular region developed, following percutaneous coronary intervention with fluoroscopic imaging. Contrary to most reported cases in the literature, which involve numerous cardiac catheterization procedures, in both patients described here the total radiation dose was given during two successive procedures, involving difficult and prolonged coronary intervention with stent implantation. In both cases, local treatment of the ulcerative lesions was insufficient, necessitating excision of the radiodermatitis area and replacement with a skin graft, with good therapeutic result. The incidence of radiodermatitis after percutaneous coronary interventions is rising with the increasing number and complexity of these procedures. The main risk factor is a long duration of fluoroscopy using the same incidence. The skin lesions encompass a wide spectrum, ranging from erythema, telangiectasia, atrophy, hyperpigmentation and hypopigmentation to necrosis, chronic ulceration and squamous cell carcinoma. The lesions can appear from 15 days to 10 years after the procedure. To prevent radiation-induced injury, the radiation dose has to be limited and monitored. Also, careful inspection of the skin at the site of exposure is necessary and the radiographic beam has to be restricted to the smallest field size. A good clinical follow-up at regular intervals is important after long and complicated procedures.

Microstaging in cutaneous melanoma

Recent papers have addressed critical issues regarding the microstaging of cutaneous melanoma. They concern the new staging proposal by the American Joint Committee on Cancer (AJCC), the presentation of new prognostic models than seem applicable in daily practice, and new immunohistochemical findings than demonstrate prognostic information independently of the conventional major factors. These issues are commented on by the Pathology Committee of the EORTC Melanoma Group.

Analysis of N- and K-ras mutations in the distinctive tumor progression phases of melanoma

Mutations in the ras genes are key events in the process of carcinogenesis; in particular, point mutations in codon 61 of exon 2 of the N-ras gene occur frequently in cutaneous melanoma. To investigate whether these mutations occur in early or late tumor progression phases, we searched for point mutations in the N- and K-ras genes in 69 primary cutaneous melanoma, 35 metastases, and seven nevocellular nevi in association with cutaneous melanoma. Lesions were microdissected in order to procure pure tumor samples from the distinctive growth phases of the cutaneous melanoma; the very sensitive denaturing gradient gel electrophoresis technique was used to visualize the mutations, and was followed by sequencing. Point mutations in the N-ras gene but not in the K-ras gene were detected on denaturing gradient gel electrophoresis. Twenty-three primary (33%) and nine metastatic (26%) melanomas showed bandshifts for N-ras. In the majority of cases, mutations occurring in early growth phases (i.e., the "intraepidermal" radial growth phase), were preserved in later growth phases (i.e., the invasive radial growth phase, vertical growth phase, and metastatic phase), which proves the clonal relationship between the successive growth phases. In three cases, however, the mutations differed between the distinctive growth phases within the same cutaneous melanoma, due to the occurrence of an additional mutation (especially in codon 61) in a later tumor progression phase. Our approach also permitted us to analyze the mutational status of nevi, associated with cutaneous melanoma. Six out of seven associated nevi carried the same sequence (mutated or wild-type) as the primary cutaneous melanoma, whereas in one case the sequence for N-ras differed between the primary melanoma and the associated nevus. In conclusion, this approach allowed us to demonstrate the clonal relationship between subsequent growth phases of melanoma and associated nevi; our results suggest that N-ras exon 1 mutations preferentially occur during early stages of tumor progression and hence may be involved in melanoma initiation, whereas those in N-ras exon 2 are found preferentially during later stages and hence are more probably involved in metastatic spread of cutaneous melanoma.

Expression of the endothelin-B receptor in pigment cell lesions of the skin. Evidence for its role as tumor progression marker in malignant melanoma

Endothelins (ETs) exert several functions in human melanocytes, including proliferation, dendrite formation, and melanin synthesis. Among the ET receptors, the non-selective endothelin-B (ETB) receptor is the major receptor in melanocytes and malignant melanoma (MM) cells. In spite of the important role of ETs and their receptors in the growth and differentiation of melanocytes, the distribution and expression levels of ETB receptors in tissue sections of benign and malignant pigment cell lesions is still unknown. We combined immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) to study ETB receptor expression in benign and malignant pigment cell lesions and in normal skin. Immunohistochemistry on paraffin-embedded tissue sections of 159 cases revealed a significant increase in intensity of ETB receptor expression from common nevi over dysplastic nevi and primary MM to metastatic MM. Quantitative PCR using realtime detection on 75 samples confirmed the immunohistochemical results. These data add the ETB receptor to the growing list of tumor progression markers in MM and suggest that ETs play a role in the progression of MM in the skin.

Expression of neurotrophins and their receptors in pigment cell lesions of the skin

The neurotrophins (NTs) are a group of growth factors involved in the development of the nervous system and presumed to play a role in neural crest-derived tumours. The expression of three NTs (NGF, BDNF, and NT-3) and their receptors (NTRs; i.e. low-affinity pan-NT receptor p75, Trk-B, and Trk-C) was studied in frozen sections of benign and malignant cutaneous pigment cell lesions, using immunohistochemistry. In order to understand the possible role of these growth factors and their receptors in the progression of primary cutaneous malignant melanomas (PCMMs), their distribution in the radial (RGP) and vertical (VGP) growth phases was particularly studied. While most of the common acquired naevi were unreactive, Spitz and blue naevi showed scattered immunoreactive cells, especially for the p75 NTR. Dysplastic naevi, but not common naevi, expressed NT-3 in their junctional component. PCMM and melanoma metastases often showed a diffuse pattern of immunostaining. NT-3 was significantly more frequently expressed in the RGP of PCMMs than in the junctional component of benign naevi, whereas more extensive immunoreactivity for NGF was found in the VGP of PCMMs, compared with the RGP; metastases more frequently expressed NGF, BDNF, and Trk-B than PCMMs. Interestingly, neurotropic melanoma expressed all NTs/NTRs except Trk-B. These immuunohistochemical data confirm suggestions from previous in vitro studies that autocrine loops of certain NTs and their respective receptors may be involved in melanoma progression; in addition, NT-3 may be involved in the junctional growth of dysplastic naevi. The precise role of these growth factors in melanoma, however, will await further functional studies.

Minimal deviation and/or naevoid melanoma: is recognition worthwhile? A clinicopathological study of nine cases

One to two per cent of primary cutaneous melanomas share clinical features with benign melanocytic and non-melanocytic skin lesions, and even at histology recognition of their malignant nature is problematic, mainly due to the lack of an intraepithelial component, their nodular aspect and the monotonous cell population throughout the lesion. These tumours were termed minimal deviation melanomas (MDMs) by Reed et al. and later naevoid melanomas by Schmoeckel et al. The name MDM suggests the concept of a more favourable outcome for these melanomas that do not (yet) show the typical features of fully evolved lesions able to metastasize, although naevoid melanomas seem to behave like 'common' melanomas. In a retrospective analysis of nine cases of MDM collected from our database and followed for a median duration of 112 months, we faced similar clinical and histological pitfalls and observed local recurrence following marginal resection. Wide excision, even of local recurrence, and therapeutic node dissection could nevertheless provide survival comparable at least to that predicted by mathematical models for patients who initially had optimal treatment.

Activated leukocyte cell adhesion molecule/CD166, a marker of tumor progression in primary malignant melanoma of the skin

Expression of activated leukocyte cell adhesion molecule (ALCAM)/CD166 correlates with the aggregation and metastatic capacity of human melanoma cell lines (Am J Pathol 1998, 152:805-813). Immunohistochemistry on a series of human melanocytic lesions reveals that ALCAM expression correlates with melanoma progression. Most nevi (34/38) and all thin melanomas studied (Clark levels I and II) did not express ALCAM. In contrast, immunoreactivity was detected in the invasive, vertical growth phase of 2 of the 13 Clark level III lesions tested. The fraction of positive lesions further increased in Clark level IV (13/19) and in Clark level V (4/4) lesions. ALCAM expression was exclusively detectable in the vertical growth phase of the primary tumor. In melanoma metastases, approximately half of the lesions tested (13/28) were ALCAM positive. According to the Breslow-thickness, ALCAM expression was observed in less than 10% of the lesions that were thinner than 1.5 mm and in over 70% of the lesions that were thicker than 1.5 mm. Our results strongly suggest that ALCAM plays an important role in melanocytic tumor progression and depict it as a new molecular marker for neoplastic progression of primary human melanoma.

Early derivation operation can restore the pancreas histology and function in chronic obstructive pancreatitis in the cat

BACKGROUND/AIMS

Obstruction of the main pancreatic duct leads to progressive obstructive and atrophying pancreatitis in the cat. The question remains whether "early" derivative procedures can halt the destructive process or not?

METHODOLOGY

Twelve cats submitted to total obstruction of the main pancreatic duct developed chronic obstructive pancreatitis as documented by histopathology. After 5 weeks, five animals underwent a caudal pancreaticojejunostomy, the others served as controls. Pancreatic histopathology and ductography was conducted in both groups, as well as tests of endocrine and exocrine functioning.

RESULTS

Three of the five cats that underwent a derivation operation died 3-5 weeks following the second operation mainly due to infection, but 2 cats could be followed-up for up to 52 weeks. The histological signs of inflammation and early fibrosis gradually disappeared and the pancreas returned to normal as assessed by histology, radiology and pancreatic function tests. In contrast, cats not submitted to the derivation procedure developed an atrophic chronic pancreatitis.

CONCLUSIONS

A desobstructive operation, carried out 5 weeks after total obstruction of the main pancreatic duct in cats, can halt the progression of chronic obstructive pancreatitis and leads to restitution of the pancreas as assessed by histology, radiology and function tests.

Representational difference analysis using minute quantities of DNA

Representational difference analysis (RDA) is a differential hybridization method which can effectively isolate unique DNA sequences from complex and highly related genomes or cDNA libraries. A major drawback of the RDA analysis is the requirement for pure driver and relatively pure tester samples, ruling out the analysis of whole tissue biopsies. To circumvent this problem, we have modified the technique for the analysis of very small quantities of DNA so that pure cell populations isolated by micromanipulation from tissue sections can be analyzed. Using this modified technique, as few as 50 diploid cells ( approximately 500 pg of DNA) can be analyzed.

Results of histo-pathologic examination of three enucleated eyes with a choroidal melanoma after strontium-90 irradiation

Three patients with a choroidal melanoma, treated with HDR (High Dose Rate) Strontium-90 brachytherapy, underwent an enucleation. Radiation effect was only visible at the irradiation zone with a brisk transition to normal tissue. Tumour was replaced by necrotic and scar tissue. The underlying sclera had a markedly reduced number of fibrocytes, but no structural alteration of the collagen stroma.

Expression of gelatinase B and the extracellular matrix metalloproteinase inducer EMMPRIN in benign and malignant pigment cell lesions of the skin

By the degradative effect on basement membrane collagen type IV, matrix metalloproteinases (MMPs) or gelatinases are important in the early invasion of malignant tumors. These enzymes may be released by the tumor cells themselves or may be derived from nearby fibroblasts that have been stimulated by the extracellular MMP inducer EMMPRIN. We studied the distribution of 92-kd gelatinase B (MMP-9) and of EMMPRIN in 33 benign and 41 malignant, paraffin-embedded pigment cell lesions using immunohistochemistry and monoclonal antibodies. In benign pigment cell lesions, EMMPRIN but not gelatinase B was expressed in cellular blue nevi whereas all other benign lesions, including common blue nevi, were negative. In malignant melanomas (MMs), both gelatinase B and EMMPRIN were variably expressed in the pure and invasive radial growth phase but not in the vertical growth phase. All lentigo maligna cases and all metastatic lesions were negative. Of MMs with thickness < 1.6 mm, 63% expressed gelatinase B and 70% expressed EMMPRIN, whereas in MMs with > 1.6 mm thickness, only 10% expressed gelatinase B and only 25% expressed EMMPRIN. We conclude that early invasion of MM is associated with de novo expression of gelatinase B and EMMPRIN by neoplastic melanocytes. Expression of EMMPRIN and MMP-9 may be partly responsible for the stromal changes observed in thin MM. Their absence in the vertical growth phase and in metastatic lesions suggests that other factors are involved in tissue degradation during later stages of tumor progression in MM. The lack of both gelatinase B and EMMPRIN in lentigo maligna may contribute to the indolent behavior of this type of pigment cell lesion.

Prognostic significance of nm23 protein expression in malignant melanoma. An immunohistochemical study

The NM23 genes, encoding for the red blood cell nucleoside diphosphate kinases A and B, have been found to serve as metastasis-suppressor genes in experimental animal models of tumour progression, and in some, but not all cancers in man. To investigate the role of NM23 in the progression of human malignant melanoma, we studied the expression and distribution of the nm23 protein with a sensitive immunohistochemical technique and a well-characterized monoclonal antibody in 41 benign pigment cell lesions and 71 uniformly treated malignant melanomas with a long follow up-up. In benign naevi, the junctional nests frequently expressed nm23 protein, whereas the immunoreactivity tended to decrease when the lesions matured. All malignant melanomas expressed nm23 protein in their vertical and/or radial growth phases, and the immunoreactivity tended to increase towards the deeper parts of the lesion. No relation was found between nm23 expression and patient outcome. In addition, nm23 was found in activated lymphoid cells, and this feature was significantly associated with a brisk lymphocytic stroma response in malignant melanomas. Our data are at variance with previous mRNA studies on malignant melanoma, and indicate that routine immunohistochemical analysis for nm23 protein on paraffin-embedded tumour tissue cannot reliably be used as a prognostic marker for patients suffering from malignant melanoma. In contrast, our findings suggest that the nm23 protein in pigment cell lesions is related to the proliferative or activated state of pigment cells, rather than to their metastatic potential.

Vascular wound healing and neointima formation induced by perivascular electric injury in mice

Vascular interventions for atherothrombotic disease frequently induce neointima formation, which can contribute to restenosis of blood vessels. As the molecular mechanisms of this process remain largely unknown, quantitative models of arterial injury in transgenic animals may be useful to study this process at the genetic level. Here, an injury model is proposed in which surgically exposed femoral arteries in mice were injured perivascularly via a single delivery of an electric current. Transmission electron microscopy, light microscopy, and immunohistochemistry revealed that electric injury destroyed all medial smooth muscle cells, denuded the injured segment of intact endothelium, and transiently induced platelet-rich mural thrombosis. A vascular wound-healing response resulted that was characterized by degradation of the mural thrombus, transient infiltration of the vessel wall by inflammatory cells, and progressive removal of the necrotic debris. Topographic analysis revealed repopulation of the media and accumulation in the neointima of smooth muscle cells originating from the uninjured borders and progressing into the necrotic center. Within 3 weeks after injury, a neointima of 0.026 +/- 0.003 mm2 (n = 7 arteries) was formed that contained a maximum of 12 +/- 1 layers of smooth muscle alpha-actin-immunoreactive cells. Evans blue staining in five electrically injured arteries revealed a denuded distance of 2.8 +/- 0.2 mm immediately after injury, which became progressively re-endothelialized from the uninjured borders to 2.2 +/- 0.08 mm (P = 0.013 vs freshly injured by analysis of variance), 0.8 +/- 0.22 mm (P < 0.001), and 0.005 +/- 0.003 mm (P < 0.001) within 2, 7, and 14 days after injury, respectively. Analysis of 5'-bromo-2'-deoxyuridine incorporation revealed that a maximum of 35 +/- 10% endothelial cells proliferated within 2 days after injury and that in the media and neointima, a maximum of, respectively, 12 +/- 2% and 18 +/- 3% smooth muscle cells proliferated within 2 weeks after injury. Thus, electric injury of arteries provides a model of vascular wound healing with arterial neointima formation and re-endothelialization that may be useful for the genetic analysis of its molecular mechanisms in transgenic mice.

CD40 is a prognostic marker in primary cutaneous malignant melanoma

CD40 is a receptor at the surface of B lymphocytes with important functions in the immune response. CD40 has also been found on a variety of carcinoma and melanoma cell lines where it has been suggested to serve as a possible receptor for mitogenic signals. We studied the expression and distribution of CD40 in paraffin sections of 71 uniformly treated malignant melanomas (MMs) with a long clinical follow-up using well known monoclonal antibodies. For comparison, 71 benign nevi were also studied. Common acquired nevi occasionally expressed CD40 in nests or single cells at the dermo-epidermal junction; no immunoreactivity was observed in the dermal part of acquired nevi, and all Spitz' nevi were entirely negative. One-third of large congenital nevi expressed CD40 in small clusters of heavily pigmented, epithelioid cells, corresponding to so-called proliferative nodules. In 41 of 71 MMs, CD40 was expressed in single or clustered neoplastic melanocytes; 9 cases showed CD40 expression only in the radial growth phase, and in 32 cases, the vertical growth phase showed CD40 expression. The same staining pattern was obtained with other anti-CD40 monoclonal antibodies, directed to different epitopes of the CD40 molecule. In 29 of 32 MMs showing CD40 in the vertical growth phase, expression of the CD40 ligand (CD40L) was studied; in 13 of these 29, CD40L was found in the same tumor areas that expressed CD40. Analysis of 28 metastases from 24 MM patients showed in the majority of cases a similar, scattered or nodular staining pattern as observed in the primary tumor. Patients expressing CD40 in the vertical growth phase of their MM did not differ significantly from CD40-negative patients with respect to any of the known prognostic parameters but showed a significantly shorter tumor-free survival. Patients with CD40+ CD40L+ MM tended to have a shorter tumor-free survival than those lacking CD40L. We conclude that CD40 represents a novel prognostic parameter in primary cutaneous MM. The co-localization of CD40 and CD40L suggests an autocrine growth loop in the vertical growth phase of MM.

Damage to duct epithelium is necessary to develop progressing lesions of chronic pancreatitis in the cat

BACKGROUND

The pathogenesis of chronic pancreatitis remains unclear. This investigation aimed to evaluate the relative importance of acinar or ductal lesions or of ductal subobstruction in the development of chronic pancreatitis in cats.

MATERIALS AND METHODS

Ethanol was injected either interstitially in the parenchyma or in the main pancreatic duct, whereas in other animals the main duct was partially obstructed to 70% of its original diameter or totally obstructed.

RESULTS

Total obstruction led to well known chronic obstructive pancreatitis and atrophy. Chronic progressive fibrosing pancreatitis developed only when the ductal epithelium was injured by intraductal injection of ethanol. It differed from the obstructive lesions, as demonstrated by biopsies taken over a one year period. Temporary, acute, or chronic-like lesions developed after intraparenchymal injection or in sub obstruction. Minor lesions were obtained in cats fed alcohol or submitted to ethanol feeding combined with partial duct obstruction. None of the laboratory tests used were very useful to detect mild chronic damage at an early stage but fecal fat and the plasma pancreolauryl test seemed the most sensitive.

CONCLUSION

Damage of the ductal epithelium represents the most important pathogenetic factor to induce chronic pancreatitis. Further refinements, and investigations with more pathophysiologic agents are necessary to ultimately lead to a reproducible model resembling the human disease.

Small, freshly arrived histiocytes in cutaneous and mucosal herpetic lesions

We report on the predominance of a special type of small histiocyte in the inflammatory infiltrate accompanying herpetic bullae. These histiocytes, which have previously been taken to be neutrophils, are freshly arrived cells with a hitherto unknown function. Until now, they have been found only in Sweet's syndrome and erythema nodosum where they form Miesscher's radial granulomas. Similar small histiocytes were found in half of those herpetic lesions with intact bullae, and in over two-thirds of ulcerated lesions in which these cells formed a palisade in the fibrinoid material covering the floor of the ulcerated vesicles. Small histiocytes, admixed with neutrophils, were in close proximity to virally infected keratinocytes. Immunohistochemical analysis confirmed their histiocytic nature. With the exception of ecthyma contagiosum (orf), similar small histiocytes were not found in other viral infections or in nonspecific ulcers of the skin. In cases of herpetic folliculitis, small histiocytes showed massive epidermotropism towards hair follicle epithelium. We conclude that cutaneous and oral herpetic infections represent yet another disease in which small, freshly arrived histiocytes occur. They may be involved in antigen presentation, or in killing of infected keratinocytes.

Immunopathogenesis of vernal keratoconjunctivitis

We have analyzed the in situ distribution of immune cells in the conjunctival biopsy specimens obtained from patients with active vernal keratoconjunctivitis (VKC). We used immunohistochemical techniques and a panel of monoclonal and polyclonal antibodies. Our data point to a complex immunopathogenesis of the disease. Distinct components involved in IgE-mediated immune mechanisms, as well as humoral and cell mediated immune mechanisms were detected in the conjunctival tissues. In addition, we investigated the presence and distribution of adhesion molecules. In the normal conjunctiva, intercellular adhesion molecule-1 (ICAM-1) was expressed only on the vascular endothelium, lymphocyte function associated antigen-1 (LFA-1) and intercellular adhesion molecule-3 (ICAM-3) on epithelial and stromal mononuclear cells, and very late activation antigen-4 (VLA-4) on a few stromal mononuclear cells. Endothelial leukocyte adhesion molecule-1 (ELAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression was not detected. In VKC a marked increase of all these antigens was observed. Strong ICAM-1 expression was induced on the basal epithelial cells, and vascular endothelium. Furthermore, about 30% of the stromal mononuclear cells expressed ICAM-1. LFA-1 and ICAM-3 were expressed on the majority of infiltrating mononuclear cells. VLA-4 expression was noted on about 25% of the stromal mononuclear cells. ELAM-1 and VCAM-1 were induced on the vascular endothelial cells. Our results suggests that increased expression of adhesion molecules in VKC promotes the recruitment of inflammatory cells through blood vessels and the cell interaction between lymphocytes and antigen presenting cells, among lymphocytes, as well as between lymphocytes and epithelial cells.

Linear IgA dermatosis: a new cause of fever of unknown origin

We describe a 60-year-old patient who presented with prolonged fever, weight loss, adenopathies and malaise. Two months later, an aphthous stomatitis and pharyngitis developed, together with ulcerations bilaterally in the groin. Two separate skin biopsies revealed the diagnosis of linear IgA dermatosis. This entity, which is well known to dermatologists but not to internists, should be added to the extensive list of disorders than can provoke the syndrome of fever of unknown origin.

Identification of Metallothionein- and parathyroid hormone-related peptide (PTHrP)-positive cells in salivary gland tumours

Ductal basal cells and myoepithelial cells (MEC) of normal salivary gland share metallothionein (MT)-positivity, while PTHrP positivity is restricted to ductal basal cells. We studied 21 benign and 4 malignant tumours in which MEC are thought to play a role using immuno-histochemical methods for detecting the presence of MT and PTHrP positive cells. In benign tumours, a shared positivity for MT and PTHrP is found in the inner layer of tubulo-ductal and trabecular structures, in part of the cells in the myxoid and chondroid matrices of pleomorphic adenoma, and in the basal epithelial lining of Warthin's tumours. In myoepithelioma almost all tumour cells demonstrate MT reactivity and a restricted positivity for PTHrP. MT-positive cells in oncocytoma were demonstrated in the periphery of some oncocytic islets, while PTHrP positivity was restricted to a few oncocytic cells. In malignant tumours, positivity for MT is found in the periphery of epithelial clusters of mucoepidermoid carcinomas, while PTHrP-positive cells are seen in cyst-like structures and scattered cells in solid arrangements of squamous cells. Although the biologic significance of the presence of MT in neoplastic cells is not yet clearly understood, MT may be necessary for the growth and differentiation in actively growing cells. The variability of MT expression in salivary gland tumours could be a reflection of the morphological heterogeneity and correlate with the degree of differentiation and maturation of the tumour cells. The observations suggest that MT may be considered an oncodevelopmental product.

Distribution of interferon-gamma receptors in normal and psoriatic skin

Recent data suggest that imbalances in production and secretion of cytokines, in particular interferon-gamma (IFN-gamma), may be crucial in the pathogenesis of psoriasis. In order to exert its role on target cells, IFN-gamma has to interact with a specific cell membrane receptor termed the IFN-gamma-receptor (IFN-gamma R). We studied the distribution of IFN-gamma Rs in frozen skin biopsies from 25 psoriatics and 5 normal controls with two unrelated monoclonal antibodies, and compared its distribution with that of the IFN-gamma-inducible HLADR- and ICAM-1 antigens. In normal skin, IFN-gamma Rs were restricted to the basal cell layer; weak staining was found on scattered mononuclear cells in the papillary dermis. In 13/25 active psoriatic lesions, additional suprabasal immunoreactive foci, and in 5/25 cases, diffuse immunoreactivity of the entire epidermis were seen. No striking topographical similarities between the site and number of IFN-gamma R+, HLADR+ and ICAM-1+ keratinocyte foci were observed, suggesting that cytokines other than IFN-gamma induce HLADR-antigens on psoriatic keratinocytes in vivo. The restricted distribution of IFN-gamma R on the germinative cell layer in normal skin confirms the role played by IFN-gamma in the normal growth regulation of the epidermis. The de novo suprabasal expression of IFN-gamma R in psoriasis argues against the current hypothesis that IFN-gamma R are down-regulated due to a local excess of IFN-gamma or transforming growth factor alpha (TGF-alpha). Whether IFN-gamma Rs in psoriatic skin are functionally normal and involved in signal transmission, remains to be studied.

Perivascular spaces in eccrine spiradenoma. A clue to its histological diagnosis

Perivascular spaces were found to represent a useful histological clue to the diagnosis of eccrine spiradenoma. They were observed in eight of nine eccrine spiradenomas but not in syringomas, nodular basal cell carcinomas, or glomangiomas. Perivascular spaces in spiradenomas consisted of variably sized spaces around one or more central blood vessels, bordered at the periphery by a palisade of tumor cells and lined at both sides by basement membrane collagen type IV. Perivascular spaces contained variable numbers of T lymphocytes in all cases and could undergo fibrosis, cystic dilatation, or hyalinization. In analogy to similar structures in thymomas, we suggest that perivascular spaces in spiradenomas are involved in the traffic of lymphocytes toward the tumor.

Bcl-2 expression in human melanocytes and melanocytic tumors

During an immunohistochemical study of the distribution of the Bcl-2 proto-oncogene product in frozen sections of normal human skin, a hitherto unrecognized strong reactivity with melanocytes was observed. This prompted us to study Bcl-2 expression in a variety of pigment lesions. In nevocellular nevi, immunoreactivity gradually diminished or even disappeared toward the deeper dermal component. In malignant melanomas of all stages and histological subtypes, the neoplastic cells expressed Bcl-2 oncoprotein, the most intense positivity being restricted to cells in the radial growth phase. Cutaneous and lymph node metastases of malignant melanomas were negative or showed only weak and focal reactivity. The specificity of the staining was confirmed by Western blotting of tissue lysates. The loss of Bcl-2 expression in the deeper parts of nevi may offer an explanation for the "maturation" and final disappearance of dermal nevocellular nevi. The expression of Bcl-2 oncoprotein by malignant melanomas adds these neoplasms to a growing list of tumors expressing this oncoprotein. Bcl-2 in malignant melanoma may play a role in tumor development by sparing the cells from apoptotic death (and thereby exposing them to secondary events) or through cooperation with other oncogenes. The lack of reactivity in metastatic melanoma suggests that mechanisms other than Bcl-2 are involved in the survival and growth of metastatic melanoma cells.

Epithelium-lining macrophages in psoriasis

Epithelium-lining macrophages are spindle-shaped cells which line the epidermis and hair follicles. We studied the distribution and phenotype of this hitherto neglected member of the dermal monocyte/macrophage system in 25 lesional psoriatic, and five normal skin biopsies. Epithelium-lining macrophages were inconspicuous in normal skin, whereas their number was increased in almost two-thirds of psoriatic cases; in nine out of 25 lesional skin biopsies, these flattened cells formed an almost continuous single-cell row at the dermo-epidermal junction. Immunophenotyping revealed that these cells expressed the leucocyte common antigen CD45, and the macrophage markers CD14, CD36 and CD4, but not CD11b. Epithelium-lining macrophages strongly expressed HLA-DR-antigens and CD11a, but lacked the Langerhans cell marker CD1, and CD34. The dermal dendrocyte marker factor XIIIa was expressed in only a minority of these cells. It is concluded that epithelium-lining macrophages represent a separate subset of dermal monocytes/macrophages with a distinct tissue localization and immunophenotype. Their restricted distribution and close association with the epidermis may suggest a role in the regulation of epidermal growth. Alternatively, the expression of several immune-associated molecules may indicate that epithelium-lining macrophages are involved in the antigen-dependent or -independent activation of T cells.

Physiological consequences of loss of plasminogen activator gene function in mice

Indirect evidence suggests a crucial role for the fibrinolytic system and its physiological triggers, tissue-type (t-PA) and urokinase-type (u-PA) plasminogen activator, in many proteolytic processes. Inactivation of the t-PA gene impairs clot lysis and inactivation of the u-PA gene results in occasional fibrin deposition. Mice with combined t-PA and u-PA deficiency suffer extensive spontaneous fibrin deposition, with its associated effects on growth, fertility and survival.

Distribution of metallothionein in normal and pathological human skin

The expression and distribution of metallothionein (MT) in frozen sections of normal and pathological human skin was studied using the monoclonal antibody L2E3 directed against MT derived from human fetal liver. Immunohistochemical staining of normal fetal and adult skin revealed strong reactivity in basal keratinocytes of epidermis and outer hair root sheath, hair matrix cells and the secretory coil, but not the exocrine portion of eccrine glands; myoepithelial cells around apocrine sweat glands were similarly stained. In epidermal hyperplasia, variable numbers of suprabasal keratinocytes were stained, whereas in interface dermatitis, interrupted staining was found in the basal layer. Weak or scattered staining was observed in squamous tumours, whereas basal cell carcinomas did not show consistent staining. The distribution of MT in normal skin was in line with the germinative role of basal keratinocytes and hair matrix cells, whereas its distribution in hyperplastic epidermis was in line with experimental animal data, and reflected the increase in the germinative pool in these conditions. It is concluded that monoclonal antibody L2E3 may serve as a valuable immunohistochemical marker in diagnostic cutaneous pathology since it labels basal keratinocytes selectively, and since it discriminates between eccrine and apocrine sweat glands.

Plasminogen activator inhibitor-1 gene-deficient mice. II. Effects on hemostasis, thrombosis, and thrombolysis

The effects of plasminogen activator inhibitor-1 (PAI-1) gene inactivation on hemostasis, thrombosis and thrombolysis were studied in homozygous PAI-1-deficient (PAI-1-/-) mice, generated by homologous recombination in D3 embryonic stem cells. Diluted (10-fold) whole blood clots from PAI-1-/- and from PAI-1 wild type (PAI-1+/+) mice underwent limited but significantly different (P < 0.001) spontaneous lysis within 3 h (6 +/- 1 vs 3 +/- 1%, respectively). A 25-microliters 125I-fibrin-labeled normal murine plasma clot, injected into a jugular vein, was lysed for 47 +/- 5, 66 +/- 3, and 87 +/- 7% within 8 h in PAI-1+/+, heterozygous PAI-1-deficient (PAI-1+/-), and PAI-1-/- mice, respectively (P = 0.002 for PAI-1+/+ vs PAI-1-/- mice). Corresponding values after pretreatment with 0.5 mg/kg endotoxin in PAI-1+/+ and PAI-1-/- mice, were 35 +/- 5 and 91 +/- 3% within 4 h, respectively (P < 0.001). 11 out of 26 PAI-1+/+ but only 1 out of 25 PAI-1-/- mice developed venous thrombosis (P = 0.004) within 6 d after injection of 10 or 50 micrograms endotoxin in the footpad. Spontaneous bleeding or delayed rebleeding could not be documented in PAI-1-/- mice after partial amputation of the tail or of the caecum. Thus, disruption of the PAI-1 gene in mice appears to induce a mild hyperfibrinolytic state and a greater resistance to venous thrombosis but not to impair hemostasis.

Monoclonal antibody to liver metallothionein: a novel marker for myoepithelial cells

Myoepithelial cells (MEC) are situated between acinar or ductal luminal cells and the basal lamina in various secretory glands, including salivary gland. The in-situ demonstration of MEC in benign and malignant conditions has long been hampered by the lack of suitable markers, most of which do not label MEC exclusively. We report here the reactivity of L2E3, a monoclonal antibody directed against liver metallothionein (MT). In the major and minor salivary glands, L2E3 stained two types of cells: a slender, elongated cell that surrounded acini; and a small, basal, cuboidal cell observed in the excretory (interlobular) ducts. Our results indicate that L2E3 represents a novel, useful marker for the immunohistochemical identification of MEC, and a highly sensitive marker for ductal basal or "reserve" cells in salivary glands.

Neuronophagia in the motor cortex in amyotrophic lateral sclerosis

This study was designed to identify which phagocytic cells in the cerebral cortex of amyotrophic lateral sclerosis (ALS) patients are involved in the process of neuronophagia. For this purpose a number of single and double immunocytochemical stains were carried out on five ALS cases which were selected on the basis of the presence of degenerative and phagocytic phenomena in the cerebral cortex. The cortical degenerative process is mainly present in the third and fifth layers and is not restricted to the fifth layer which contains the cell bodies of the Betz cells. The present study indicates that a number of cells are involved in the process of phagocytosis in ALS. Resident macrophages (from microglial or perivascular origin) and astrocytes seem to play an immunologically-mediated role in the disappearance of neurons. Some of the cells involved in the degenerative process, i.e. rounded macrophages and microglia, expressed major histocompatibility class II antigen. The phagocytic cells in neuronophagia were phenotypically identical to perivascular macrophages and not to microglia. Therefore, the process of phagocytosis of neurons appears to be primarily the task of the perivascularly located macrophage.

The transitional zone between limbus and peripheral cornea. An immunohistochemical study

PURPOSE

The authors investigated the phenotypic characteristics of basally located "transitional cells" in peripheral superior cornea, characterized previously by their coexpression of cytokeratin 19 and vimentin and their negativity for AE5.

METHODS

Twenty adult human corneas were studied, using in situ immunohistochemical techniques and a panel of specific monoclonal antibodies against various surface and cytoplasmic molecules.

RESULTS

The transitional cells shared staining characteristics with limbal basal cells in their expression of alpha 6 beta 4-integrin, metallothionein, AE1, and transferrin receptor.

CONCLUSIONS

These "transitional" epithelial cells exhibit a unique phenotype differing from that of the surrounding basal epithelial cells in the peripheral cornea but analogous to that of limbal basal cells. These findings further corroborate the hypothesis that, at least from an immunohistochemical point of view, transitional cells in the superior peripheral cornea exhibit stem cell characteristics.

A new epithelial cell type in the human cornea

PURPOSE

To study the expression of intermediate filaments in the human cornea.

METHODS

Light and electron microscopic and immunohistochemical studies were performed on 20 corneas from subjects of various ages.

RESULTS

A hitherto unrecognized epithelial cell population emerged from the immunohistochemical studies. Epithelial cells were invariably present in the superior cornea, whereas the nasal, temporal, and inferior segments almost lacked these cells. They were situated at the transition between peripheral cornea and limbus, and occurred as small groups in the basal epithelium. On electron microscopy, they were recognized by their marginated nuclear chromatin, large nucleoli, prominent bundles of intermediate filaments, and numerous hemidesmosomes and desmosomes. Immunohistochemistry on frozen sections revealed a unique intermediate filament make-up: ie, strong co-expression of vimentin and cytokeratin 19; other intermediate filaments, including cytokeratins 3, 4, 6, 7, 8, 10, 13, and 18 were negative. Finally, the cells lacked ultrastructural and immunohistochemical features of melanocytes, neuroendocrine cells, Langerhans' cells, and leukocytes.

CONCLUSIONS

A new epithelial cell type in the human cornea is described with characteristic morphologic and immunohistochemical features. According to their particular segmental distribution, restricted localization at the junction between cornea and limbus, and expression of an "early" intermediate filament profile, it is tempting to speculate that they represent stem cells of the human cornea. Further studies are aimed to characterize their phenotype and function more extensively.

Integrins as differential cell lineage markers of primary liver tumors

This study analyzed new cell lineage markers for the differential diagnosis between hepatocellular carcinoma (HCC) and cholangiocarcinoma (ChC), as well as the potential pathways of cell-cell and cell-extracellular matrix interactions of neoplastic liver cells during tumor spread and invasion, by comparing the expression of (VLA) integrins, vitronectin receptor, and neural cell adhesion molecule in normal, inflamed, and neoplastic human liver biopsies. All cases of liver cell adenoma and well-differentiated HCC expressed the same set of integrins as observed in normal liver tissue, i.e., VLA-alpha 1 and VLA-beta 1. Poorly differentiated HCC also expressed VLA-alpha 1 and VLA-beta 1, but in addition de-novo expressed VLA-alpha 2, VLA-alpha 3, VLA-alpha 6 and vitronectin receptor. All cases of well-differentiated ChC expressed an identical integrin immunoprofile as observed in normal bile duct epithelium, i.e., VLA-alpha 2, VLA-alpha 3, VLA-alpha 6, VLA-beta 4 and vitronectin receptor, whereas poorly differentiated ChC showed a markedly decreased expression of these integrin subunits. VLA-alpha 1 was constantly absent from all cases of ChC, whereas VLA-beta 4 was never expressed by HCC. Neural cell adhesion molecule, exclusively expressed by proliferating reactive bile ductules in cholestatic and regenerating liver, was constantly absent from both malignant neoplasms. In conclusion, the integrin make up of various liver tumors closely follows that of their normal counterparts. Differences in integrin receptor expression vary according to the cellular origin of the tumors and are associated with a poor differentiation. Our findings suggest that immunohistochemical staining for VLA-alpha 1 and VLA-beta 4 integrin subunits, which highlight the cellular phenotype of the two neoplasms, might be a helpful tool in the differential diagnosis between HCC and ChC.

Papuloerythroderma: report of a European case

A case of papuloerythroderma in a 74-year-old woman is presented. She had blood eosinophilia (up to 4,130 mm3), elevated serum IgE (2,369 IU/ml) and responded to oral steroids.

Practical suggestions for successful immunoenzyme double-staining experiments

Many methodologies exist to perform an immunoenzyme double staining. Hence, the practical problem arises as to which of these methods is optimal for one's own experimental design. A process of selection is described which is derived from our own practical experience. First, a general strategy is outlined for the handling of tissue sections to be used for multiple staining methods. Secondly, the selection of an appropriate immunoenzyme double-staining concept is made using a flow chart. Thereafter we give criteria for the definitive selection of an immunoenzyme double-staining protocol based on the characteristics of the tissue or cell type under study. Particular attention is given to the selection of appropriate detection systems, applying enzymes or gold particles, and good contrasting colour combinations. The problems of visualizing co-localization using immunoenzyme double staining are dealt with, and suggestions are made to adapt the method, if necessary, in order to optimize it.

Can hepatocytes serve as 'activated' immunomodulating cells in the immune response?

During the last few years, there has been a growing evidence that hepatocytes are not merely 'passive' target cells for immunological attack by effector T-cells, but may play a more 'active' role in the initiation and perpetuation of the immune response. Immune modulators released by inflammatory cells at the site of inflammation, as well as the eliciting antigen itself, are able to modulate the phenotype of hepatocytes. This would result in abnormal cytokine production and/or cytokine/receptor expression, as well as active synthesis and display of surface immune 'activation' markers and adhesion molecules, which act as co-stimulatory signals for T-cell activation. These accessory functions involve multiple molecular pathways of cell-cell interactions, which in turn will enable hepatocytes to play a role as 'accessory' cells in both the afferent and efferent arms of the cell-mediated immune response.

LAM-1/Leu 8 antigen is expressed on portal, but not on lobular intrahepatic mononuclear cells in inflammatory liver disease

The expression of the selectin receptor LAM-1/Leu 8 was analysed in normal and in inflamed liver tissue, and its expression on mononuclear inflammatory cells was correlated with their topographical distribution in various compartments of the inflamed liver, in order to obtain new insights on possible molecular mechanisms involved in the traffic of mononuclear inflammatory cells throughout the diseased hepatic parenchyma. In normal liver tissue, few scattered mononuclear cells in portal and lobular parenchyma corresponded to both CD4+ and CD8+, as well as to CD45RA+ (2H4+) naive and CD45RO+ (UCHL1+) memory T cells, and were LAM-1/Leu 8+. In acute and chronic inflamed liver biopsies, CD45RO+ (UCHL1+) CD4+ and CD8+ memory T cells largely predominated in both portal and lobular parenchyma. The expression of LAM-1/Leu 8 antigen on these memory T cells varied according to their localization in the liver parenchyma, and it was not correlated with specific aetiological causes. In acute hepatitis, the vast majority of T lymphocytes were LAM-1/Leu 8-. In chronic active hepatitis, memory T cells in portal tracts expressed LAM-1/Leu 8, whereas virtually all intralobular T cells accumulating in areas of periportal and intralobular inflammation were LAM-1/Leu 8-. In chronic persistent hepatitis, the LAM-1/Leu 8+ T cells largely predominated among the numerous mononuclear inflammatory cells within enlarged portal tracts, whereas LAM-1/Leu 8- T cells were restricted to areas of intralobular 'spotty' inflammation. Therefore, two phenotypical populations can be recognized among the memory T cells in inflamed liver tissue, according to their topographical localization: LAM-1/Leu 8+ T cells predominating in portal tracts, and LAM-1/Leu 8- T cells predominating in the lobular parenchyma. These data show that during their migration through the inflamed liver parenchyma, memory T lymphocytes undergo phenotypical changes (LAM-1/Leu 8 shedding) according to their localization in different liver compartments (portal tracts vs. lobular parenchyma), suggesting multiple cellular and molecular mechanisms involved in the regulation of the leucocyte traffic through inflamed liver tissue.

Localization of the cytoadhesin integrins in the human cornea. An immunohistochemical study using monoclonal antibodies

Cell-matrix interactions play a fundamental role in normal and pathological conditions. They can be mediated by the cytoadhesin subgroup of the integrin superfamily of adhesion molecules. Its members include the vitronectin receptor (VNR) and the platelet glycoprotein IIb/IIIa (GP IIb/IIIa). Both receptors are composed of an alpha-chain (alpha v and alpha IIb, respectively) coupled to a beta 3-chain. Using in situ immunohistochemistry and monoclonal antibodies, the authors studied the distribution of GP IIIa (common beta 3-chain), GP IIb/IIIa (alpha IIb-chain) and VNR (alpha v-chain) in normal and pathological corneal tissues. In the normal cornea, the limbal vascular endothelium was weakly alpha v-positive. Occasionally, faint and granular staining was seen in the epithelium. In the pathological samples, an upregulated expression of the alpha v-chain was noticed on the corneal epithelium as well as on fibroblasts and corneal endothelium. The alpha IIb and beta 3-chains were consistently absent. These data suggest that expression of the VNR-alpha v-chain in the human cornea is modulated by soluble factors released during inflammation and wound healing. Dissociation of expression of the alpha v and beta 3-chains suggests usage of an alternative beta-chain by the VNR-alpha v-chain.

Immunohistological alterations in muscle of patients with amyotrophic lateral sclerosis: mononuclear cell phenotypes and expression of MHC products

Muscle biopsy specimens from 15 autopsied patients with the isolated form of amyotrophic lateral sclerosis were examined by routine histological and immunocytochemical methods using a panel of monoclonal antibodies directed against differentiation and activation markers of immunocompetent cells. In 12 cases, cellular infiltrates consisting mainly of T-cells and macrophages were seen. Both CD8+ and CD3+ cells, in juxtaposition with OKM1+ macrophages, were particularly seen in the atrophied parts of muscle. The majority of the T-cells appeared to be of the CD4+ T-helper/inducer type, whereas the CD8+ T-suppressor/cytotoxic cells were only rarely and focally present. On the other hand, B-, NK- and K-cells were infrequently seen. Most of the T-cells and macrophages surrounding the atrophied muscle fibers were in an activated state, as indicated by their intense HLA DR expression. In addition, some angulated degenerated fibers showed strong endomysial positivity for HLA DR in the regions where T-cells and macrophages were present in clusters. The immunoreactive changes in ALS-associated muscle atrophy are very similar to those reported for exercise-induced damage and some forms of myositis. The present study shows that the expression of major histocompatibility complex products and the relative numbers of infiltrating immunocompetent cells are closely associated with the extent of destruction of muscle fibers in ALS.

In situ immunohistochemical analysis of cell adhesion molecules on human corneal endothelial cells

Interaction of leucocytes with human corneal endothelial cells (HCECs) can be observed in several clinicopathological conditions, such as uveitis, keratitis, and corneal graft rejection. Since leucocyte-endothelial cell interactions involve various adhesion receptors we have analysed the expression and distribution pattern of the neural cell adhesion molecule (NCAM), the intercellular adhesion molecule-1 (ICAM-1), the vascular cell adhesion molecule-1 (VCAM-1), the endothelial leucocyte adhesion molecule-1 (ELAM-1), and the cluster of differentiation antigen-44 (CD44) on flat preparations of normal and organ-cultured HCECs. NCAM and ICAM were constitutively expressed on HCECs whereas VCAM-1, ELAM-1, and CD44 were absent from normal HCECs. However flat mounts of HCECs from organ-culture preserved corneas showed a mosaic-like distribution pattern of VCAM-1 and ELAM-1 positive cells and garland-like clusters of CD44 positive cells. We suggest that modulation of ELAM-1, VCAM-1, and CD44 expression on HCECs may contribute to the regulation of leucocytes-HCECs interaction in the case of anterior segment inflammation.

Hepatic expression of type A and type B receptors for tumor necrosis factor

We have examined the in-situ distribution of type A and type B receptors for tumor necrosis factor (TNF) in normal and diseased human liver biopsy specimens. In normal liver tissue, no or very small amounts of TNF receptors were found. In acute and chronic inflammatory liver diseases, a strong up-regulation of the expression of both TNF receptors was found on hepatocytes, bile duct epithelium, sinusoidal lining cells and mononuclear inflammatory cells. With immunoelectronmicroscopy, all these cells showed cytoplasmic, in addition to membranous staining, suggesting active synthesis of the receptor or, alternatively, internalization of the receptor and its ligand. This up-regulated expression of both type A and type B receptors for TNF was similar in acute and chronic active hepatitis, and was not related to the etiology of the liver disease, nor restricted to areas of liver inflammation. Our results indicate that hepatocytes, sinusoidal endothelial cells, bile duct epithelial cells and mononuclear inflammatory cells, by displaying receptors for TNFs, represent target cells for both these cytokines. Up-regulated expression of type A and type B receptors for TNFs endows these cells with augmented responsiveness for the pleiomorphic biological activities of these cytokines during liver injury.

Induction of intercellular adhesion molecule-1 (CD54) on human hepatoma cell line HepG2: influence of cytokines and hepatitis B virus-DNA transfection

Human hepatocyte expression of intercellular adhesion molecule-1 (ICAM-1) (CD54) was studied in vitro by exposing the well differentiated human hepatoblastoma cell line HepG2 to various cytokines. In addition, hepatitis B virus (HBV)-DNA transfected HepG2 cells were also analysed. Expression of ICAM-1 on HepG2 cells was then revealed with an immunohistochemical procedure. Untreated HepG2 cells were unreactive, but showed strong cytoplasmic ICAM-1 immunoreactivity after treatment with interferon-gamma (IFN-gamma). This induction was completely inhibited by addition of a neutralizing antibody directed to IFN-gamma. IL-1, IL-6, tumour necrosis factor-alpha (TNF-alpha) and IFN-alpha, used alone or in combination, did not induce ICAM-1 expression, neither did they inhibit the IFN-gamma-induced expression of this adhesion molecule on HepG2 cells. Untreated hepatitis B virus-DNA transfected HepG2 cells expressed membranous ICAM-1. These results indicate that IFN-gamma is the main cytokine trigger for ICAM-1 expression on HepG2 cells, suggesting that in areas of liver inflammation this adhesion molecule is up-regulated on hepatocytes by locally released IFN-gamma. In addition, expression of ICAM-1 by hepatitis B virus-DNA transfected HepG2 cells suggests other, still unknown, triggering mechanisms in the induction of such adhesion molecules, for instance gene activation by viral genome, or autocrine virus-induced hepatocellular cytokine production.

Distribution of the VLA family of integrins in normal and pathological human liver tissue

The "very late activation" (VLA) subgroup of the integrin superfamily of adhesion molecules plays a central role in cell-cell and cell-matrix interactions. The six different VLA dimers known so far consist of a common beta subunit and a variable alpha (1 to 6) subunit. They serve as receptors for laminin, collagen, and fibronectin or function as adhesion molecules for leukocytes and are therefore of great significance in embryogenesis, growth and repair, and in leukocyte recirculation. The distribution of the common beta and the variable alpha chains of the VLA were studied in normal, inflammatory, and cholestatic liver biopsy samples. In normal liver tissue, vascular endothelia express alpha 1, 2, 3, 5, and 6; bile duct epithelium alpha 2, 3, 5, and 6; connective tissue stroma alpha 1 and 2; hepatocytes alpha 1 and 5; sinusoidal lining cells alpha 1, 2, and 5; and mononuclear cells alpha 4. Whereas bile ducts and vascular endothelia do not show relevant changes in alpha chain expression in liver diseases, hepatocytes de novo express membranous alpha 3 and 6 in inflammatory liver diseases. In view of the role of the VLA-3 and VLA-6 as laminin receptors, this finding is in line with the production of laminin in active liver disease. Moreover, de novo expression of "bile duct type" alpha 2, 3, and 6 on periportal hepatocytes in cholestatic liver disease likely illustrates a phenotypic switch of hepatocytes towards bile duct epithelium during cholestasis.

Distribution of very late activation integrins in the human cornea. An immunohistochemical study using monoclonal antibodies

There is growing evidence that cellular adhesion mechanisms characterized by cell-cell and cell-matrix interactions are a fundamental process in the immunobiology of the cornea. Interactions with various extracellular matrix components are mediated by the very late activation (VLA) subgroup of the integrin superfamily of adhesion molecules. The six different VLA dimers known thus far consist of a common beta 1 subunit and a variable alpha (1 to 6) subunit. They serve as receptors for laminin (alpha 3 and alpha 6), collagen (alpha 2 and alpha 3), and fibronectin (alpha 4 and alpha 5). Using in situ immunohistochemistry and monoclonal antibodies, the distribution of the common beta 1 and the variable alpha-chains of VLA molecules was studied in normal human cornea and in cases with scarring or subepithelial/retrocorneal fibrous tissue. Epithelial cells were VLA-beta 1 and VLA-alpha 2, -alpha 3, -alpha 4, -alpha 5, and -alpha 6 positive. This is consistent with their intercellular adhesion and may aid in their attachment to the basement membrane which is composed of collagen, laminin, and fibronectin. Keratocytes in normal stroma expressed only the common beta 1-chain and no detectable alpha-chains. In regions of scar or fibrous tissue, however, an upregulated expression of the alpha-chains was detected. The VLA- alpha 1, -alpha 3, -alpha 4, and -alpha 5 were expressed in young fibrous tissue; in older lesions, VLA- alpha 1, -alpha 2, -alpha 3, -alpha 4, and -alpha 5 could be detected. The corneal endothelium showed a strikingly strong positivity for all VLA integrins.(ABSTRACT TRUNCATED AT 250 WORDS)

Memory T cells represent the predominant lymphocyte subset in acute and chronic liver inflammation

T cells can be divided into two main phenotypic subpopulations-i.e., the CD45RA-positive (2H4-positive) "naive" subset and the CD45RO-positive (UCHL1-positive) "memory" subset. In light of this recent functional reinterpretation of T-lymphocyte subpopulations, we reinvestigated the composition of the inflammatory infiltrate in liver biopsy specimens from patients with acute and chronic hepatitis. In normal liver, the few scattered mononuclear cells present in portal tracts and in the intralobular parenchyma consisted of both CD45RA-positive (2H4-positive) naive and CD45RO-positive (UCHL1-positive) memory T cells. In inflammatory liver diseases, portal tract and periportal and intralobular areas of inflammation consisted virtually only of CD45RO-positive (UCHL1-positive) memory T cells, which strongly expressed the CDw29 (4B4) antigen, and the adhesion molecules LFA-1, CD2, LFA-3, CD44 and VLA-4 and the activation marker human leukocyte antigen-DR. These results indicate that activated memory T cells represent the predominant subpopulation of lymphocytes in areas of liver inflammation. Memory T cells strongly express various homing receptors and adhesion molecules, which probably allow them to accumulate at inflammatory sites and to strengthen interaction with target cells. Furthermore, the increased number of memory T cells with enhanced interferon-gamma production in areas of liver inflammation may contribute to the maintenance and up-regulation of immune responses occurring in inflammatory liver diseases.