Immunofluorescent localization of type IV collagen and laminin in human skin and its application in junctional zone pathology

A combined physicochemical approach towards human tenocyte phenotype maintenance

During in vitro culture, bereft of their optimal tissue context, tenocytes lose their phenotype and function. Considering that tenocytes in their native tissue milieu are exposed simultaneously to manifold signals, combination approaches (e.g. growth factor supplementation and mechanical stimulation) are continuously gaining pace to control cell fate during in vitro expansion, albeit with limited success due to the literally infinite number of possible permutations. In this work, we assessed the potential of scalable and potent physicochemical approaches that control cell fate (substrate stiffness, anisotropic surface topography, collagen type I coating) and enhance extracellular matrix deposition (macromolecular crowding) in maintaining human tenocyte phenotype in culture. Cell morphology was primarily responsive to surface topography. The tissue culture plastic induced the largest nuclei area, the lowest aspect ratio, and the highest focal adhesion kinase. Collagen type I coating increased cell number and metabolic activity. Cell viability was not affected by any of the variables assessed. Macromolecular crowding intensely enhanced and accelerated native extracellular matrix deposition, albeit not in an aligned fashion, even on the grooved substrates. Gene analysis at day 14 revealed that the 130 kPa grooved substrate without collagen type I coating and under macromolecular crowding conditions positively regulated human tenocyte phenotype. Collectively, this work illustrates the beneficial effects of combined physicochemical approaches in controlling cell fate during in vitro expansion.

The dermal sheath: An emerging component of the hair follicle stem cell niche

Hair follicles cyclically regenerate throughout adult mammalian life, owing to a resident population of epithelial hair follicle stem cells. Stem cell (SC) activity drives bouts of follicle growth, which are periodically interrupted by follicle regression and rest. These phases and the transitions between them are tightly spatiotemporally coordinated by signalling crosstalk between stem/progenitor cells and the various cell types of the microenvironment, or niche. The dermal papilla (DP) is a cluster of specialized mesenchymal cells that have long been recognized for important niche roles in regulating hair follicle SC activation, as well as progenitor proliferation and differentiation during follicle growth. In addition to the DP, the mesenchyme of the murine pelage follicle is also comprised of a follicle-lining smooth muscle known as the dermal sheath (DS), which has been far less studied than the DP yet may be equally specialized and important for hair cycling. In this review, we define the murine pelage DS in comparison with human DS and discuss recent work that highlights the emergent importance of the DS in the hair follicle SC niche. Last, we examine potential therapeutic applications for the DS in hair regeneration and wound healing.

A Contemporary View on Felix Pinkus' Concept of the Vitreous Membrane

Introduction

Felix Pinkus' concept of the vitreous membrane (VM) published in 1927 describes circular folds protruding into the outer root sheath (ORS), which, in his opinion, serve as interdigitations between the outer root sheath (ORS) and the VM. This concept currently seems to have fallen into oblivion.

Objective

To determine the origin and possible function of the VM in the proliferation and vascularization of the hair follicle (HF).

Methods

Serial investigation of healthy skin probes with histological (hematoxylin & eosin and periodic acid-Schiff) and immunohistochemical examination (Ki67, CD56, CD8, and collagen IV) were performed.

Results

Morphological variations of the VM in various HFs such as protrusions and folds, the latter unilateral, bilateral or circular, some acute-angled, were found. Similarly, protrusions of the VM into the ORS were observed, that consisted of capillary tissue together with perifollicular tissue and VM mimicking minimal variants of the dermal papilla.

Conclusions

Pinkus' concept of the VM is revisited, reproduced and possible functions are proposed. Since these structures are found in a HF region with a high metabolic dynamism, they may be involved in differentiation or nutrition, or else be formed as a result of pressure arising from outgrowing hair shafts.

Collagen IV in Normal Skin and in Pathological Processes

CONTEXT

Type IV collagen is a type of collagen found primarily in the skin within the basement membrane zone. The type IV collagen C4 domain at the C-terminus is not removed in post-translational processing, and the fibers are thus link head-to-head, rather than in a parallel fashion. Also, type IV collagen lacks a glycine in every third amino-acid residue necessary for the tight collagen helix. Thus, the overall collagen-IV conformation is structurally more pliable and kinked, relative to other collagen subtypes. These structural features allow collagen IV to form sheets, which is the primary structural form found in the cutaneous basal lamina. There are six human genes associated with collagen IV, specifically COL4A1, COL4A2, COL4A3, COL4A4, COL4A5 and COL4A6. The aim of this review is to highlight the significance of this protein in normal skin, and in selected diseases.

RESULTS

The alpha 3 protein constituent of type IV collagen is thought to be the antigen implicated in Goodpasture's syndrome, wherein the immune system attacks the basement membranes of the renal glomeruli and pulmonary alveoli. In addition, mutations to the genes coding for type IV collagen lead to the Alport syndrome. Furthermore, autoantibodies directed against denatured human type IV collagen have been described in rheumatoid arthritis, scleroderma, and SLE. Structural studies of collagen IV have been utilized to differentiate between subepidermal blistering diseases, including bullous pemphigoid, acquired epidermolysis bullosa, anti-epiligrin cicatricial pemphigoid, and bullous lupus erythematosus. Collagen IV is also of importance in wound healing and in embryogenesis.

CONCLUSIONS

Pathological studies have demonstrated that minor structural differences in collagen IV can lead to distinct, clinically different diseases.

A monoclonal antibody established from the immunization of basal cell carcinoma (BCC) tissues reacts to the intercellular space of BCC and hair follicles

To detail the histogenetic relationship between basal cell carcinoma (BCC) and hair follicles, a monoclonal antibody, coded as MMKB-1 and established from immunization of mice by human basal cell carcinoma (BCC) tissues, was immunohistochemically studied in tissues of BCC and squamous cell carcinoma (SCC) of the skin, as well as in normal human skin tissues. On 1M-NaCl-split normal human skin tissues, it reacted against both the epidermal and the dermal sides of the basement membrane zone (BMZ). This monoclonal antibody reacted to the BMZ and intercellular space (ICS) of the solid, superficial, and fibrosing types of BCC cell nests, but, in SCC tumor cell nests, it reacted exclusively to the BMZ. Immunoelectron microscopic studies revealed that the corresponding antigen of the monoclonal antibody was distributed in the hemidesmosomes and the anchoring fibrils along the BMZ of the normal human skin and the desmosomes of the BCC cell nest. The monoclonal antibody also reacted to the ICS of the lower outer root sheath and hair matrix. We discussed the histogenesis of BCC and hair follicles, referring to the results of the staining patterns of MMKB-1 monoclonal antibody and to other studies suggesting a histogenetic relationship between BCC and hair follicles.

Basal cell carcinoma cells resemble follicular matrix cells rather than follicular bulge cells: immunohistochemical and ultrastructural comparative studies

To detail the histogenetic relationship between basal cell carcinoma (BCC) and hair follicles, we immunohistochemically compared BCC cells to follicular matrix cells and follicular bulge cells using a panel of monoclonal antibodies against melanocytes, cytokeratins, subepidermal extracellular matrix components, and bullous pemphigoid (BP) sera, as well as using electron microscopy. Cytokeratin expression patterns were not consistent with the variety in types of cytokeratins and in cases of BCC. The distribution of some extracellular matrix components was not only linear along the interfaces of BCC tumor nests and stroma, and follicular matrix and follicular papilla; granular deposits were also seen in the stroma and follicular papilla, whereas they were only linearly distributed along the follicular bulge. The BP antigens and integrin alpha 6, which were absent in BCC and follicular matrix, were expressed in the follicular bulge area. Electron microscopically, hemidesmosomes were poorly organized in these three tissues, but the lamina densa was incomplete in BCC and follicular matrix, whereas the lamina densa in the follicular bulge area was continuous. These morphologic similarities between BCC and follicular matrix cells, and coexistence of melanocytes in the BCC tumor nest strongly suggest the differentiation of BCC toward the follicular matrix cells.

The management of solitary trichoepithelioma versus basal cell carcinoma

Currently, all lesions diagnosed clinically as basal cell carcinoma (BCC) are treated by the excision of the lesion with 3-4 mm margins followed by histopathological examination to assess clearance and confirm the diagnosis. We present the findings of surgical incisional and excisional biopsy of three young patients diagnosed on clinical examination as having BCC, who were found on histological examination to have trichoepithelioma. Whilst it may be possible to distinguish the features of trichoepithelioma in incisional biopsy specimens on morphological grounds alone it is often difficult, and immunohistochemical staining, to delineate the features of the basement membrane, provides useful additional information in the histological diagnosis. As trichoepithelioma is more common in the young it should be considered in the differential diagnosis in young patients presenting with BCC-like lesions of the periocular tissues. This subgroup of patients should have incisional biopsy carried out, and if the diagnosis of trichoepithelioma is confirmed the lesion may be excised with a small margin of healthy tissue, thereby facilitating surgical repair.

Presence and interpretation of vascular immune deposits in human skin: the value of direct immunofluorescence

Direct immunofluorescence investigation of the skin is an easy and valuable technique to establish the diagnosis immune complex vasculitis. Vascular immune deposits can be found in 60-80% of all cases. Absence of vascular immune deposits, however, does not exclude vasculitis per se, since the dynamics of the vasculitic process limit their presence in time. Knowledge of these dynamics is indispensable for both the clinician and the interpreter. Several practical options are discussed that may increase sensitivity. The specificity of vascular immune deposits has become a complex matter. Different immunoglobulin classes have different specificity, indicating that specificity also depends on the relative incidence of individual immunoglobulin classes. Some of these relative incidences seem to have changed over the years. Furthermore, several non-vasculitic diseases and conditions have now been described, that may show fluorescent pictures similar to vasculitis and thus decrease specificity.

The epidermal basement membrane in basal cell carcinoma: an immunohistochemical study

An immunohistochemical study of basal cell carcinomas of varying histological type, using a panel of antibodies to constituents of the epidermal basement membrane, showed marked deficiencies in the expression of the antigens identified by the antibodies LH7.2, GB3 and G71. There was no correlation between loss of immunoreactivity to these antibodies and the histological features of the tumour.

Immunohistochemical studies on the localization of fetal antigen 2 (FA2), laminin, and collagen type 4 in basal cell carcinoma

The localization of fetal antigen 2 (FA2), a recently described basement membrane (BM) associated antigen, was studied by immunohistochemical techniques in 21 basal cell carcinomas (BCC). In both superficial and infiltrating BCC, FA2 was located in a broad diffuse band around the tumor elements and in close contact with the BM. Compared to normal skin, a more extensive distribution of FA2 was seen in BCC. In the infiltrating BCC, FA2 staining was also present in the interstitial stroma between the tumor islands. FA2 was absent in areas with inflammatory cell infiltrates and elastoid degeneration. Epithelial and tumor cells were FA2 negative. The distribution of FA2 was clearly different from that of laminin and collagen type 4. Collagen type 4 and laminin were present as a continuous linear band corresponding to the BM surrounding the tumors. The close contact to the BM and the increased content of FA2 in the reactive stroma around BCC suggest that FA2 is involved in the matrix and/or BM changes taking place during tumor growth and invasion.

Revised clinical and laboratory criteria for subtypes of inherited epidermolysis bullosa. A consensus report by the Subcommittee on Diagnosis and Classification of the National Epidermolysis Bullosa Registry

Inherited epidermolysis bullosa encompasses a number of diseases, with the common finding of blister formation after minor mechanical trauma to the skin. In some forms significant, if not eventually fatal, extracutaneous disease activity may occur. In recent years application of newer technologies has contributed substantially to an overall understanding of this collection of inherited diseases. Concurrently, many new phenotypes have been recognized, in part the result of ongoing prospective patient registries in the United States and abroad. Unfortunately, this has resulted in a massive literature that may appear to be confounded by seemingly excessive or arbitrary subdivision of epidermolysis bullosa variants. With these concerns in mind a subcommittee was established by the National Epidermolysis Bullosa Registry to summarize the current literature and to make recommendations as to the best clinical and laboratory criteria for the practical diagnosis and subclassification of patients with inherited epidermolysis bullosa.

Biology of basal cell carcinoma (Part I)

Basal cell carcinoma is the most common malignancy in humans. Although rarely metastatic, it is capable of significant local destruction and disfigurement. This two-part article reviews the current understanding of basal cell carcinoma biology. Part I examines significant clinical, histologic, and ultrastructural features that relate to invasive potential. Genetic characteristics, including tumor growth rate, chromosomal abnormalities, and oncogene presence, are discussed, and expression of important cell and matrix proteins, including keratin, fibronectin, and HLA antigens, are reviewed. Further topics to be explored in Part II include host immunologic responses, theories of pathogenesis, and valuable second-line therapeutic regimens for treatment of multiple cancers.

The subbasement membrane distribution of type IV collagen in normal human skin

Samples of normal human skin were obtained from 48 sites in 26 subjects ranging in age from 2 to 85 years. The samples were examined by indirect immunofluorescence and immunoelectron microscopy using anti-human type IV collagen antibodies produced by immunizing rabbits with type IV collagen extracted from human placenta. Fluorescence was observed as granular or fine fibrous patterns, not only in the basement membrane at the dermo-epidermal junction, around the vessels, and the accessory organs of the skin, but also in the dermal regions in the vicinity of the basement membranes. This suggests the presence of type IV collagen in the dermis deep to the basement membrane. Ultrastructurally, the extrabasal lamina distribution of type IV collagen was noted as a partial distribution around the fibroblasts that existed close to the basal lamina. These findings are considered to be important in examining the function of this collagen in the dermis and the dynamics and metabolism of the basement membrane under normal and abnormal conditions.

Fibronectin and laminin in Achilles tendon

Ten intact and 22 ruptured Achilles tendons were studied by immunohistochemical techniques. In intact tendons, both fibronectin and laminin were found in vascular walls, myotendineal junction, and endomysium, but not in the connective tissue of the tendons. In ruptured tendons the distribution of laminin was not changed. Fibronectin deposits, on the contrary, could be detected on the tear surface and in the collagen fibers of the ruptured tendons.

Basal cell carcinoma xenografts in nude mice: studies on epithelial differentiation and stromal relationships

Thirty-three basal cell carcinomas (BCC) were transplanted into athymic mice, and foci of tumour were identified in 17 grafts recovered after intervals of 2-5 months. Fifteen of these xenografts contained apparently normal differentiated epithelia, considered to derive from elements within the original tumours. The level of differentiation was very close in original and corresponding xenograft BCC. Morphologically recognizable 'specialized' stroma was present in some but not all xenografted BCC, and was also present in some grafts containing only differentiated elements. A monoclonal antibody specific to human type IV collagen showed intact epithelial and also vascular basement membranes within the graft. Surprisingly, mouse cells were found to line these vessels, and the stroma around normal and neoplastic epithelial islands was a mixture of mouse and human cells, with no consistent composition. These observations question the proposed dependence of BCC on its 'specialized' stroma.

Prenatal diagnosis of dominant and recessive dystrophic epidermolysis bullosa: application and limitations in the use of KF-1 and LH 7:2 monoclonal antibodies and immunofluorescence mapping technique

Prenatal diagnosis is now possible for junctional and recessive dystrophic forms of epidermolysis bullosa (EB); however, there is no similar published experience for dominant dystrophic EB, although data with KF-1 monoclonal antibody suggests that both forms of dystrophic EB can be identified at least postnatally with this unique probe. We now report our experience with light microscopy, electron microscopy, immunofluorescence mapping, and KF-1 and LH 7:2 monoclonal antibodies, in both a mother with dominant dystrophic EB and her fetus at risk, and in a fetus previously shown to be affected with recessive dystrophic EB. KF-1 and LH 7:2 antigens were absent in recessive dystrophic EB fetal skin, identical to findings observed postnatally. LH 7:2 was normally expressed in a mother with dominant dystrophic EB and in her fetus at risk for this disease. In contrast, while KF-1 antigen was abnormally expressed in the affected mother, it was normally expressed in only 1/7 fetal biopsies despite the fact that this fetus was shown by light and electron microscopy and immunofluorescence mapping to be unaffected with dominant dystrophic EB. We conclude that 1) transmission electron microscopy can be used to prenatally exclude the diagnosis of dominant dystrophic EB (Cockayne-Touraine variety), 2) immunofluorescence mapping is an accurate technique for prenatal as well as postnatal diagnosis of EB, and 3) KF-1 cannot by itself be used as an accurate probe for the prenatal diagnosis of dominant dystrophic EB, due to the apparent variability in the time for the normal expression of KF-1 in fetal skin during the second trimester.

Immunohistochemical studies of basal cell carcinomas transplanted into nude mice

Xenografting into nude mice forms a system for analysis of human tissues under experimental conditions. In this study, normal skin samples and basal cell carcinomas were investigated, prior to and after transplantation, using immunofluorescence methods with antibodies against keratins, laminin, and collagen type IV. Three groups of transplants were studied: intact tissue samples, human epithelium (either normal or neoplastic) recombined with normal human dermis and, human epithelium recombined with normal mouse dermis. Transplants recovered after 3 weeks showed the following characteristics. The xenograft system was satisfactory in terms of host survival and rate of successful tissue recovery except for recombinants between human epithelium and mouse dermis. Intact and recombined samples of normal skin retained their preexisting patterns of architecture, cytodifferentiation, and basement membrane staining. Solid nonfibrosing basal cell carcinomas showed altered architecture and differentiation of both the epithelium and the basement membrane zone after transplantation: the solid tumor pattern changed towards spreading of tumor cells, a more squamous differentiation pattern was apparent and was confirmed by reactivity with antibodies against large keratins. Discontinuities of the basement membrane zone were detected with antibodies against laminin and collagen type IV. These changes were seen in both intact and recombined tumor transplants.

The biology of basal cell carcinomas--a revisit and recent developments

This paper will review some of the present information on the biology of basal cell carcinoma. Recent developments include a better understanding of the basement membrane components surrounding the tumor nodules, as well as identifying the most actively dividing cells in solid basal cell carcinoma by autoradiographic techniques. The implications of a recently developed animal model will also be discussed.

Basal cell carcinomas grown in nude mice produce and deposit fibronectin in the extracellular matrix

Epidermal cells in vitro produce and deposit fibronectin (FN) in the pericellular matrix. Such FN production by epidermal cells may be involved in vivo in wound reepithelialization, tissue morphogenesis, and growth of epithelial tumors. The purpose of this study was to examine whether the FN, previously shown to be within and surrounding human basal cell carcinoma (BCC) lobules, was in part the product of epidermal-derived tumor cells. To examine this question we took advantage of our ability to grow human BCC in nude mice. Since we could demonstrate that all stromal cells surrounding the BCC were of mouse origin, antibodies specific for human FN would distinguish epithelial-derived FN from mesenchymal-derived FN. Five solid BCCs were implanted subcutaneously in nude mice. Growing tumors were removed after 60 days, snap-frozen, sectioned on a cryostat, and verified microscopically as BCC. The Hoescht DNA stain, which can distinguish mouse and human nuclei, demonstrated that mouse, not human, fibroblasts occupied the stroma surrounding each tumor lobule. Sections of all 5 BCCs were stained by immunofluorescence and immunoperoxidase techniques with antibodies to bullous pemphigoid (BP) antigen, laminin (LM), and FN. BP antigen and LM were present at the basement membrane zone (BMZ) of all tumor lobules as previously described for in situ BCC. FN staining was present along the BMZ, within the tumor lobules, and in the surrounding stroma. Antibodies to human FN were passed over a mouse FN affinity column to absorb antibodies which cross-reacted with mouse FN. The resultant antibody preparation, which was specific for human FN in this system, continued to demonstrate FN along the BMZ and within the tumors, but failed to stain FN in more distant stroma. Epidermal-derived cells, therefore, can synthesize and deposit FN in vivo in adjacent extracellular matrix. We speculate that this FN matrix may facilitate growth of BCC in this model.

Basement membrane in Kaposi's sarcoma: an immunohistochemical and ultrastructural study

Basement membranes were investigated in early angiomatous and late sarcomatoid stages of Kaposi's sarcoma (KS). Seven frozen skin biopsies of KS from five elderly Mediterranean people and one renal allograft recipient were labelled, using an immunoperoxidase technique, for basement membrane-specific macromolecules, laminin and type IV-collagen. Twenty-seven other frozen cutaneous lesions including haemangio and lymphangiosarcomas, benign vascular tumours, and various epithelial, melanocytic, fibrohistiocytic, fibrosarcomatous and muscular tumours were processed in the same way. In addition an ultrastructural study was performed in two cases of KS, one haemangiosarcoma and one lymphangiosarcoma. Intense labelling was observed for both type IV-collagen and laminin, which appeared closely co-distributed, in all areas of KS. Staining pattern was often regular and continuous around neoplastic vessels in early lesions of KS, as in benign vascular lesions, whereas in late nodular lesions large amounts of basement membrane components were present in intercellular spaces between densely aggregated spindle cells. In contrast, ultrastructural examination disclosed early disruption of basement membranes around neoplastic vessels, and occasional fragments of external lamina were seen at the interface between KS spindle cells and collagen. Similar results were obtained in angiosarcomas both by immunohistological and ultrastructural study. In the comparative group, laminin and type IV-collagen were present, in significantly fewer quantities and in various distinctive patterns, in epithelial, melanocytic, fibrohistiocytic and muscular tumors. This study deals with basement membrane modifications in early and late lesions of KS and provides further evidence in favour of the endothelial nature of the spindle cells of KS.

Monoclonal antibodies and the skin biopsy: current and potential clinical applications

Monoclonal antibodies are becoming increasingly useful in the clinical diagnosis and/or treatment of a number of unrelated diseases. Discussion will be directed to those monoclonal antibodies recognizing antigens within the skin which appear to have either proven or potential application in the diagnostic evaluation of the skin biopsy.

Cicatricial pemphigoid, bullous pemphigoid, and epidermolysis bullosa acquisita antigens: differences in organ and species specificities and localization in chemically-separated human skin of three basement membrane antigens

Bullous pemphigoid, cicatricial pemphigoid, and epidermolysis bullosa acquisita are three autoimmune diseases characterized by the presence of subepidermal blisters, in vivo-bound immunoreactants along the dermoepidermal junction, and variably detectable circulating anti-basement membrane autoantibodies. In order to better characterize the antigen(s) defined by cicatricial pemphigoid sera, indirect immunofluorescence was performed on a variety of human organs, skins of different animals, and on human skin chemically-split within the lamina lucida, comparing sera from cicatricial pemphigoid patients with sera from these two other blistering diseases. Sera from patients with each disease bound to the dermoepidermal junction of every laboratory animal species examined. In contrast, more mucosal tissues were bound by anti-basement membrane autoantibodies from patients with cicatricial pemphigoid and epidermolysis bullosa acquisita than from patients with bullous pemphigoid, consistent with the marked tendency for mucosal involvement in patients with the former two diseases. In addition, one of the cicatricial pemphigoid sera stained basal cell surfaces as well as dermoepidermal junction. Differences were also apparent in the staining of chemically-split human skin. The combined findings suggest that cicatricial pemphigoid and bullous pemphigoid antigens are distinct despite their common localization within the lamina lucida of the dermoepidermal junction. These data also suggest the presence of at least two different cicatricial pemphigoid antigens.

Epidermolysis bullosa: variability of expression of cicatricial pemphigoid, bullous pemphigoid, and epidermolysis bullosa acquisita antigens in clinically uninvolved skin

Indirect immunofluorescence was performed on skin from 13 patients with epidermolysis bullosa (EB) (simplex, 6; junctional, 2; dystrophic, 5) to compare the expression of 3 basement membrane components, bullous pemphigoid (BP) antigen, cicatricial pemphigoid (CP) antigen, and epidermolysis bullosa acquisita (EBA) antigen, in clinically uninvolved tissue. In addition, expression of laminin, type IV collagen, and KF-1 antigen was also evaluated. Whereas laminin, type IV collagen, and KF-1 antigen were each detectable in EB skin in a manner identical to that previously reported, marked variability was noted in the expression of BP, CP, and EBA antigens. However, no correlation was noted comparing lack of expression of any one of these latter antigens with either of the remaining two. Of these 3 antigens, BP antigen was the least often detectable, particularly in skin from patients with EB simplex. The lack of detectable BP antigen in EB simplex skin appeared to correlate with more extensive disease involvement and/or younger patient age. These findings may, therefore, limit the usefulness of BP serum in immunofluorescence mapping. Additionally, the disparity in expression of basement membrane antigens defined by BP and CP sera suggests that BP antigen and CP antigen are distinct entities.

Lectin-binding abnormalities in the stromal and epithelial components of basal cell carcinoma

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Alteration of the extracellular matrix of cultured human keratinocytes by transformation and during differentiation

We have investigated the production of 3 extracellular matrix proteins (fibronectin, laminin and entactin) and glycosaminoglycans (GAGs) by keratinocytes derived from human squamous-cell carcinomas (SCCs). All the SCC lines retained the ability to synthesize fibronectin, laminin and entactin, and to incorporate them into an extracellular matrix. In some of the SCC lines fibronectin production was higher than in normal keratinocytes, and in most lines laminin production was equal to or higher than that seen in normal keratinocyte strains. All the tumorigenic SCC lines produced less entactin than normal keratinocytes. Five out of 7 SCC lines showed a shift in GAG production compared with normal keratinocytes, so that in these lines heparan sulphate was the major GAG as opposed to hyaluronic acid in the normal keratinocytes. As these changes could have been a consequence of the reduced differentiation found in the SCC lines, we fractionated normal keratinocytes into 4 size classes corresponding to different stages of differentiation, using Percoll gradient centrifugation. It was found that the ability to produce these extracellular matrix glycoproteins and GAGs was lost as keratinocytes terminally differentiated. However, this did not explain the matrix changes seen in the SCC lines, since the undifferentiated normal keratinocytes produced a normal pattern of extracellular matrix components. Nonetheless, the loss of extracellular matrix production may well explain the reduction in substratum adhesiveness which occurs as keratinocytes terminally differentiate.

Histologic distribution of staining by a monoclonal antibody (psi-3) in psoriasis and occurrence of psi-3 antigen in other cutaneous diseases

psi-3 is a monoclonal antibody that recognizes a 135,000 molecular weight structural component of maturing keratinocytes in psoriasis (the psi-3 antigen) but fails to bind to any constituent of keratinocytes in normal epidermis. This paper describes the occurrence of the psi-3 antigen in a variety of dermatopathologic conditions using immunoperoxidase (biotin-avidin-peroxidase) and immunofluorescence methods which show excellent concordance. In 35 of 36 specimens of psoriasis vulgaris, psi-3 antibody consistently immunolabels the cytoplasm of keratinocytes above the basal layer. At the edges of psoriatic plaques, psi-3 antibody staining extends for a variable distance into lesion-free epidermis. A similar pattern has been found in a certain number of other conditions described in the paper, including squamous cell carcinoma and condyloma acuminatum, but not Darier's disease, basal cell carcinoma, nor lamellar ichthyosis. In all but one condition, the outermost or basal layer of cells is never stained. The only disease in which the lowermost cell layer is stained is a lichen planus-like lesion. The occurrence of psi-3 antigen cannot be correlated with any histologic feature of psoriasis such as acanthosis, loss of the granular layer, or hyperproliferation. The antigen appears to be a unique keratinocyte constituent which is expressed in certain pathologic conditions and which is not detected by any other histologic or immunophenotyping method. It is a potentially valuable addition to the panel of antibodies available for characterizing epithelial cells.

Pathogenetic studies in bullous pemphigoid--review of the literature and our own results

Bullous pemphigoid (bP) is a blister‐forming disease, probably of autoimmune nature. Its genetic background has not been established yet. Associations with other autoimmune diseases and, to some extend, with malignant tumors are noteworthy. The blisters are located subepidermally in the lamina lucida between the cytoplasmic membrane of the basal cells and the lamina densa of the basement membrane. The bP antigen, which is produced by basal cells, serves as an attachment factor and can be liberated into the blister fluid, probably by serine proteases from leucocytes. The formation of antigen‐antibody complexes is favoured afterwards. Freely circulating bP antibodies, mostly of the IgG class, are fixed in the skin tissue in vivo and in vitro and bind complement. Components of the classical complement pathway as well as of the amplification loop are activated locally in the skin tissue and fixed. The content of immune complexes is increased in the serum and in the blister fluid. They partially consist of specific bP antigen‐antibody complexes. The determination of the entire bP antibody titer (after immune complex splitting) correlates well with the clinical course of the disease.

Chemotactic factors for neutrophils and eosinophils are released into the blister fluid after complement activation, so that leucocyte attraction is mediated. Deviations of humoral and cellular immune reactivity have not been studied sufficiently. There might be an immune modulating effect of immune complexes and other serum factors on T‐lymphocytes due to steric hindrance of surface receptors. In vivo and in vitro models in rabbit cornea, skin explants, and frozen sectioned skin tissue suggest that the interaction of circulating bP antibodies with the bP antigen followed by complement activation and attraction of neutrophils might be the primary immunopathological mechanism, producing an immune complex mediated inflammation.

Desmoplastic trichoepithelioma: clinico-pathological features and immunohistochemical study of the basement membrane proteins, laminin and type IV collagen

Six desmoplastic trichoepitheliomas (DT) from four patients were studied immunohistochemically, using antibodies to the human PI fragment of laminin and the 7S domain of type IV collagen. The staining of the basement membrane around the tumour clusters was distinct and continuous in most areas, but there were discontinuities and a granular appearance of the basement membrane in the areas of keratinized cysts and calcification around some unorganized epithelial cell nests. The discontinuities of the basement membranes may be a sign of epithelial degeneration or altered differentiation rather than malignancy.

Immunohistochemical localization of epidermal basement membrane laminin and type IV collagen in bullous lesions of dermatitis herpetiformis

Antibodies against the human basement membrane proteins, laminin and the 7-S domain of type IV collagen, were used to study the epidermal basement membrane in lesional skin from four patients with dermatitis herpetiformis. The staining pattern of both antigens was mostly fragmented and sometimes absent on papillary microabscesses, but when present it was attached to the epidermal basal cells. On papillary microblisters and larger blisters the staining of both antigens showed discontinuities and was located in the floor of the blister, except for two cases where tiny fragments of laminin staining were also seen in the roof of larger blisters. These results suggest that blister formation in dermatitis herpetiformis takes place between the epidermal basal cells and the basement membrane.

Basement membrane laminin and type IV collagen in various benign and malignant adnexal tumors of the skin: an immunohistochemical study

Thirty benign and seven malignant adnexal tumors of the skin and one lymph node metastasis were stained for laminin and type IV collagen with rabbit antibodies against the human basement membrane (BM) proteins using the immunoperoxidase technique. Fifteen of the benign sweat gland, sebaceous gland, and hair follicle tumors showed a continuous and distinct BM around the tumor aggregates. The cylindromas and eccrine spiradenomas seemed to produce excessive amounts of BM material, part of which was seen as amorphic patches within the tumor cell clusters, whereas the trichofolliculomas, trichoepitheliomas, and pilomatrixomas showed an absence of BM from many areas. In syringomas, in addition to the tubular structures surrounded by a continuous BM, undifferentiated cell nests containing granular BM material were present. They probably represent primitive structures obtaining during early development into tubules. The seven malignant tumors and the only metastasis studied here all contained small, narrow strips of BM material extracellularly between the infiltrating tumor clusters. Only in two cases was faint staining for laminin found within the cells. The pepsin pretreatment of the formalin-fixed, paraffin-embedded samples had most probably degraded the intracytoplasmic BM material in most cases. The BM defects were found to be associated with malignancy and low differentiation of the adnexal skin tumors, as reported previously for other tumor types, but a partial loss of BM was also associated with high differentiation in some benign adnexal tumors.

Basement membrane components outline the tumour islands in cylindroma

The main histological feature of cylindroma is the deposition of sheaths of a 'hyalinized' material contiguous to the tumour cell clusters. Although ultrastructural studies of this material have revealed a basement membrane-like structure, its exact nature has remained unclear. Using immuno-staining with affinity-purified antibodies directed against distinct basement membrane components, we have shown that type IV collagen and laminin are major constituents of this zone. In addition, cell culture studies indicated that both proteins are synthesized by the tumour cells. The immunohistological data make it clear that the tumour matrix between the tumour cell islands is composed not only of basement membrane components, but also is composed of other connective tissue constituents, i.e. type I and III collagen and fibronectin.

Changes in the extracellular matrix components fibronectin and laminin during immune rejection of skeletal muscle

Extracellular matrix is known to play an important role during development and maintenance of various tissues. In the present study, changes in two extracellular matrix glycoproteins, fibronectin and laminin, were investigated in skeletal muscle undergoing immune rejection. Purified antibodies against fibronectin and laminin were used to analyze the matrix by indirect immunofluorescence at various intervals after transplantation of extensor digitorum longus muscle in rats. Fibronectin and laminin were localized in the pericellular basement membrane zone of the normal myofibers; however, the cytoplasm was devoid of both glycoproteins. Transplanted muscle grafts underwent a process of degeneration and then an initial regeneration during the first 7 days. This regeneration effort ceased with the onset of muscle rejection in 14-day transplants. At this time, fibronectin was seen in the cytoplasmic region as well as the extracellular matrix of myofibers and myotubes. At later time intervals, an increased intensity of staining for fibronectin was seen throughout the rejected muscle. In muscle grafts undergoing regeneration but not rejection (i.e., nonantigenic grafts), such an increase in the presence of fibronectin was not seen ( Gulati et al., 1982). The distribution of laminin did not change during the rejection process and was localized in the basement membrane zone of myofibers and myotubes, although the overall configuration of the basement membranes was deformed and collapsed. It appears that the basement membranes are resistant to degradation, and staining for laminin persists in rejected muscle. These results show marked changes in the extracellular matrix of muscle undergoing rejection. The appearance of fibronectin during the initial stages of muscle rejection may have a causal relationship to the process of immune defence mechanism; however, the exact role of fibronectin remains elusive.

Discontinuity of the basement membrane in fibrosing basocellular carcinomas and basosquamous carcinomas of the skin: an immunohistochemical study with human laminin and type IV collagen antibodies

Thirteen basocellular carcinomas (BCC) of different histologic types and 5 basosquamous carcinomas (BSC) of the skin were stained for laminin and type IV collagen with rabbit antibodies against the human basement membrane (BM) proteins, using an immunoperoxidase technique. The BM around the tumor aggregates contained both laminin and type IV collagen, and was continuous and distinct in all the nonfibrosing BCCs but indistinct or interrupted in the fibrosing BCCs and BSCs. The BM was not influenced by the focal adnexal differentiation of the BCC cells. The disintegrity of the BM in the fibrosing BCCs and BSCs may reflect some kind of disturbance in the interaction between the neoplastic epithelium and the connective tissue stroma, and be connected with the more aggressive nature of these tumors compared with ordinary BCCs. Thus local aggressive behavior seems to be accompanied by defects in the BM.

Extracellular matrix components produced by SV40-transformed human epidermal keratinocytes

The production of fibronectin, laminin and glycosaminoglycans (GAGs) has been investigated in normal and SV40-transformed human epidermal keratinocytes. Normal keratinocytes produced small amounts of laminin and fibronectin and three classes of GAGs; hyaluronic acid, heparan sulphate and chondroitin sulphate, hyaluronic acid being the major GAG. The SV40-transformed keratinocytes retained their cell-surface laminin and fibronectin, and in some cases showed elevated levels when compared to normal keratinocytes. All the transformants showed a shift in GAG production from hyaluronic acid to heparan sulphate, so that in all SV40-transformed keratinocytes heparan sulphate was the major GAG. These results demonstrate that the loss of extracellular matrix, which normally occurs in transformed fibroblastic cells, is not a feature of SV40-transformed human keratinocytes.

Collagen type distribution and macromolecular organization of connective tissue in different layers of human skin

Human skin is composed of several layers which are characterized by a specific macromolecular organization of connective tissue. Three approaches were used to quantify the collagen types present in each of the different layers: biochemical analysis of authentic tissue, metabolic labeling of organ cultures, and metabolic labeling of fibroblast monolayers. We obtained reproducible evidence for a somewhat higher ratio of type III/type I collagen synthesis in the papillary dermis and the subcutaneous fat compared to the reticular layer. Constant amounts of alpha 1 (I) trimers and type V collagen were found in all layers. The degree of hydroxylation of lysine in either type I or type III collagen was the same in any layer of the skin.

Fibronectin in basal cell epithelioma: sources and significance

Nodular basal cell epitheliomas (BCE) contain fibronectin both within tumor nodules and at the nodule-stroma interface (basement membrane zone). Fibronectin within or at the periphery of tumor nodules could be derived from the tumor cells, from entrapped stroma, or from plasma. The present study was designed to elucidate the source(s) of fibronectin within BCE nodules. If stromal entrapment occurred to any great extent, von Willebrand factor VIII:Ag-stained blood vessels within tumor nodules should be evident by immunofluorescence techniques. Likewise, if plasma proteins were deposited in BCE, the tumor nodules should stain with fluorescein-conjugated antifibrinogen antibodies. Therefore, 6 basal cell epitheliomas were double labeled with rhodamine-conjugated antihuman fibronectin and fluorescein-conjugated antihuman factor VIII:Ag or fluorescein-labeled antihuman fibrinogen. Fibronectin was present in a linear disposition along the margin of tumor lobules and as a fine filamentous deposit in the central portions of tumor tissue. There was no evidence of fibrinogen or factor VIII:Ag in any of the tumor lobules. Factor VIII:Ag was present in a granular pattern within blood vessel walls that coursed between tumor nests. An indirect immunoperoxidase technique using rabbit antihuman fibronectin and peroxidase-labeled goat antirabbit IgG demonstrated that fibronectin within the central portion of the tumor lobules was closely associated with the tumor cells. The absence of fibrinogen and factor VIII:Ag within the tumor tissue indicates that the fibronectin is probably not plasma- or stroma-derived while immunoperoxidase data suggest that fibronectin may be a product of BCE cells.

KF-1 monoclonal antibody defines a specific basement membrane antigen defect in dystrophic forms of epidermolysis bullosa

The monoclonal antibody, KF-1, identifies a noncollagenous constituent of the lamina densa of the basement membrane zone (BMZ) of skin. In order to determine whether this BMZ constituent is affected in epidermolysis bullosa (EB), a mechanobullous skin disease often resulting in marked disfigurement, we have examined skin from patients with various forms of this disease for binding by KF-1 as well as for binding by polyclonal antibodies to laminin, type IV collagen, and bullous pemphigoid antigen, three other known BMZ components of normal skin. In all specimens from patients with simplex and junctional forms of EB, all four antibodies bound normally. In contrast, absent or diminished KF-1 binding was noted in all skin specimens from patients with dystrophic EB; antibodies directed against the other BMZ constituents, however, bound normally. This suggests that KF-1 may play a role in the structural integrity of normal skin and its absence or diminution may be important in the pathogenesis of lesion formation in dystrophic EB.