Epidermal intercellular staining with fluorescein-conjugated phytohemagglutinins

Expression of the L-fucose moiety on epidermal keratinocytes in psoriasis induced by the Koebner phenomenon: a sequential study

The expression of Ulex europaeus agglutinin (UEA I) binding sites on cell-surface glycoproteins has been used as a marker for terminal differentiation. Increased number of UEA I binding sites of L-fucose specificity have been demonstrated in psoriatic epidermis. The results of lectin-binding studies in a series of biopsies taken sequentially (0 min, 5 min, 24 h, 7 days and 8 weeks) after tape-stripping of uninvolved skin in 12 psoriatic patients (three of whom were taking diltiazem, a calcium blocker at the time of the study) and six controls are presented. UEA I binding sites, which were expressed on the granular layer and upper layers of the stratum spinosum of pre-tape stripped uninvolved skin in psoriatic individuals, were progressively more numerous, with the expression of the L-fucose moiety on the lower stratum spinosum keratinocytes in the 7-day post-tape-stripping biopsies and 8-week biopsies, correlating with a moderate and marked increase in the proliferative index, respectively. In the Koebner-negative and non-psoriatic individuals who failed to develop psoriasis after tape-stripping, the UEA I binding sites were not expressed on keratinocytes of the lower stratum spinosum in any of the biopsies, although a mild increase in the proliferative index was noted in the 7-day biopsies. Our data suggest that the increased commitment of keratinocytes to terminally differentiate may be involved in the psoriatic process.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of the L-Fucose Moiety on Infrainfundibular Follicular Keratinocytes of Terminal Follicles, Its Decreased Expression on Vellus and Indeterminate Follicles of Androgenetic Alopecia, and Re-Expression in Drug-Induced Hair Regrowth

The distribution of various glycoprotein molecules on the surface of follicular keratinocytes was studied with a panel of lectins with specificity for various sugar moieties on biopsy specimens from both bald/balding scalp and normal occipital scalp, of 23 patients with androgenetic alopecia as well as on biopsies of normal forearm skin of four patients. The most significant differences between bald and normal scalp biopsy were noted with Ulex europaeus agglutinin I (UEA I). We noted an increased (91.8% +/- 3.1; mean +/- SE) expression of UEA I binding sites on the infra-infundibular follicular keratinocytes in anagen terminal scalp hairs, compared to 28.5% +/- 5.2 in the indeterminate (anagen) hairs of balding scalps, and 23.2% +/- 6.3 in the anagen follicles of vellus fore-arm hairs. By contrast, the telogen hairs demonstrated minimal UEA I staining: 4.0% +/- 0.8, mean +/- SE in telogen scalp hairs, 1.8% +/- 0.5 in telogen hairs of balding scalps (0% in completely bald scalps, in which all the hairs were in the telogen phase), and 1.9% +/- 0.2 in telogen forearm hairs. The percentage of UEA I staining correlated with the length of the infra-infundibular follicles in all cases studied. In three cases of hair regrowth after hair growth promotors, the UEA I staining increased to 80.6% +/- 6.1 in anagen hairs and correlated with increased length of infra-infundibular follicles. Our data indicate that there are 1) marked differences between anagen and telogen follicles in UEA I binding to infra-infundibular follicular keratinocytes; 2) the percentage of UEA I staining reflects the size (length) of the infra-infundibular hair follicle; and 3) the anagen follicles of balding scalps (indeterminate hairs) show UEA I staining resembling that exhibited by anagen follicles of vellus hairs.

Cohesion and desquamation of epidermal stratum corneum

This article attempts to provide a comprehensive review on the roles of various classes of molecules in the cohesion and desquamation of the stratum corneum. In the first part of this monograph we review the field of epidermal differentiation in vivo and vitro, describing the expression and functions of a number of key structural molecules that characterize the process. In the second part we emphasize terminal differentiation and the biogenesis of the stratum corneum. The stratum corneum is a cell layer unique to fully differentiated squamous epithelia such as skin. While it is a dead stratum, it nevertheless is in a homeostatic process of continual shedding and renewal in synchrony with basal cell replication. It is also a degradative layer containing many proteinases and glycosidases in which a variety of intracellular and intercellular macromolecules are degraded. We highlight the molecules localized within the intercorneal matrix that are most likely to play a role in cohesion and desquamation, including: glycoproteins, lipids and enzymes. Because it is difficult to study the stratum corneum and desquamation in the native tissue, we discuss a number of model systems that have been used. The stratum corneum can be dispersed into single squames in different ways; these include mechanical dispersion as well as agents such as detergents and enzymes. The solubilized molecules and the structures remaining can then be studied as to their specific roles in desquamation. Using this approach it is possible to reconstitute multilayered structures that resemble a real stratum corneum. We have shown that glycoproteins play a key role in squame reaggregation and that this process can be modulated with amino sugars in a lectin-like fashion. Cohesion and desquamation can also be studied in tissue culture. Depending on the culture system, the extent of terminal differentiation and squame accumulation varies. Yet desquamation does not normally occur. It can be induced however by the inclusion of exogenous agents such as IFN-gamma which are found in the native epidermis but are absent in vitro. Modulation of desquamation by other exogenous agents is likely to yield further knowledge of how shedding occurs in vivo. Insight has also come from studies of scaling skin disorders. The glycoprotein and lipid profiles are altered in the stratum corneum in many diseases of aberrant terminal differentiation. A number of abnormalities in the levels of cytokines and growth factors have also been reported in the lesional tissue of such diseases.(ABSTRACT TRUNCATED AT 400 WORDS)

bis-(beta-chloroethyl)sulfide (BCES)-induced changes in epidermal cell homeostasis in vitro

A rat cutaneous keratinocyte culture system was developed to study the effects of the vesicant bis-(beta-chloroethyl)sulfide (BCES) on the homeostasis of cell proliferation and differentiation. Lectins were used to reveal cell surface carbohydrate changes as the keratinocytes differentiate. In the newborn rat epidermis, the isolectin, Griffonia simplicifolia I-B4 (GS I-B4), binds to basal cell surfaces. Ulex europeus agglutinin I (UEA) binds to the surfaces of spinous and lower granular cells and is therefore considered an indicator of keratinocyte differentiation. A fluorometric assay was developed which determines the ratio of bound UEA to bound GS I-B4 (the UEA/B4 ratio) in primary monolayer cultures of rat cutaneous keratinocytes maintained in low Ca2+ medium. The UEA/B4 ratio was found to be a representation of the relative sizes of the differentiating and proliferating cell compartments in the monolayer cultures, respectively (W.W. Ku and I.A. Bernstein, 1988, Exp. Cell Res., 175, 298-316). Monolayer cultures exposed for 1 hr to BCES at Day 1 exhibited a dose-related increase in the UEA/B4 ratio at Day 7 when compared to solvent controls. The results from the analysis of lectin binding sites showed a decrease in GS I-B4 binding with little or no change in UEA binding as a result of BCES exposure, contributing to the increase in the UEA/B4 ratio. BCES-exposed monolayers also showed early perturbations in replicative DNA synthesis as revealed by autoradiography. Subsequent to the perturbations in replicative DNA synthesis was an inability of BCES-exposed cultures to produce cells into the monolayer through mitosis. In addition to an increase in the UEA/B4 ratio, BCES-exposed monolayers also showed a dose-related loss of DNA, with the appearance of enlarged cells at Day 7. These enlarged cells failed to show evidence of DNA synthesis, with groups of these cells showing intense UEA staining with only faint GS I-B4 staining. Overall, exposure to low concentrations of BCES appeared to disrupt the normal homeostasis of cell proliferation and differentiation in this monolayer culture system. This disruption was primarily through a reduction in the fraction of germinative (basal) cells with concomitant retention of some early differentiated cells, presumably early spinous or spinous cells.

Concanavalin A and Lens culinaris agglutinin binding patterns in normal and neoplastic sebaceous epithelium

Formalin-fixed, paraffin-embedded tissue sections of normal skin, sebaceous hyperplasia, nevus sebaceus, sebaceous adenoma, and sebaceous carcinoma were studied by means of biotinylated and FITC conjugated concanavalin A (Con A) and Lens culinaris agglutinin (LCA). At relatively high concentrations of these lectins, all cutaneous epithelial cells were stained. As the concentration of LCA was lowered, there was a corresponding decrease in the intensity of staining of all epithelial cells. With lowered concentrations of Con A, staining of sebaceous epithelium remained strongly positive, while staining of other epithelia decreased in a manner similar to that seen for LCA. These staining patterns were seen in normal and neoplastic tissues. Both Con A and LCA are known to bind to alpha-D-mannopyranosyl and alpha-D-glucopyranosyl residues of glycoproteins and glycolipids. The difference in staining of sebaceous epithelial cells by Con A and LCA suggests that the binding of these lectins is not determined strictly by the presence of alpha-D-mannopyranosyl or alpha-D-glucopyranosyl residues, but is modified by side-chain substitution on the monosaccharides and/or by the oligosaccharide which contains the particular monosaccharide. Whichever event is operative, a saccharide moiety is present on the surface of mature sebaceous cells which has a strong affinity for Con A.

Antibody-mediated rosette formation of epidermal cells with leukocytes in pemphigus vulgaris

Human peripheral-blood leukocytes (PBLs) were found to form rosettes with cultured human epidermal cells or a mouse epidermal cell line (Pam cells), but not with fibroblasts, when preincubated with heat-inactivated sera from patients with pemphigus vulgaris. Increased rosette formation was observed, however, when untreated sera were used for passive sensitization. Complement was not required for this reaction, because purified IgG fractions from a protein-A/Sepharose column retained the ability to induce rosette formation. Blocking experiments with alpha-methyl-mannoside suggested that a carbohydrate moiety is involved in the binding of sensitized cells to epidermal cells. Thus, human PBLs can adhere to cultured mouse epidermal cells in the presence of PV IgG antibodies.

Lectins

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Histochemical observations of lectin-binding in experimental carcinomas in mouse submandibular glands

Peroxidase-conjugated lectins were used for the histochemical detection of carbohydrates in experimental carcinomas of mouse submandibular glands. Induced carcinomas, 43 lesions from 25 cases, were examined histochemically with galactose-binding lectins (PNA and RCA-1), N-acetyl-galactosamine-binding lectins (DBA and SBA), a fucose-binding lectin (UEA-1), and a N-acetyl-glucosamine-binding lectin (WGA). In non- or slightly keratinized squamous-cell carcinomas, the lectin binding of PNA, RCA-1, DBA, SBA, and WGA was weak in tumor epithelia, and UEA-1 binding was slight. In highly keratinized squamous-cell carcinomas, lectin binding was increased in tumor epithelia, but no reaction was noted in completely keratinized regions. Desquamated materials in lumens of tumors gave an intense stain with lectins. Stromal connective tissue, including collagen fibers and basement membranes stained intensely. Lectin binding to submandibular carcinomas was different from binding to granular convoluted tubules and the striated ducts of the normal submandibular gland.

Histochemical studies on Concanavalin A-binding in experimental carcinoma of the mouse submandibular gland

The lectin, Concanavalin A(Con A) has been used to localize specific sugar residues (D-glucose, D-mannose and D-fructose) in premalignant lesions and squamous-cell carcinomas induced following cryosurgery of the mouse submandibular gland. The original Con A-horseradish peroxidase (HRP) technique as well as its combination with periodate oxidation and subsequent reduction by borohydrate were used to compare the epithelial elements during submandibular gland carcinogenesis. Granules in the granular convoluted tubule cells which were weakly reactive to the Con A-HRP method were not present in the premalignant duct like structures. The epithelium of premalignant lesions, duct-like structures, multicystic lesions, and squamous-cell carcinomas were positive for the cell-surface and intercellular substances; and basement membranes and stromal fibers were also positive. The results indicated that throughout malignant transformation of the ductal segments, premalignant epithelia lost Con A-HRP-staining granules and that Con A-binding patterns in induced squamous-cell carcinomas were similar to those found in squamous-cell epithelium.

Electrophoretic and immunoelectrophoretic analysis of pig epidermal plasma membrane glycoproteins

he glycoprotein components of a plasma membrane-enriched fraction from pig epidermis were isolated by deoxycholate extraction and affinity chromatography on concanavalin A (ConA)-Sepharose 4B. Reduction with 5% 2-mercaptoethanol, electrophoresis on 10% polyacrylamide slab gels, and periodic acid-Schiff (PAS) staining resolved the major glycoproteins into at least 5 components of Mr 180K, 150K, 130K, 100K and 85K. Neuraminidase removed essentially all the sialic acid whether or not the glycoproteins were solubilized with detergents. Neuraminidase treatment increased the electrophoretic mobility of most components on one-dimension polyacrylamide gels, indicating their sialoglycoprotein nature. An antiserum was raised in rabbits against isolated epidermal plasma membrane glycoproteins. Isolated immunoglobulins were used in crossed immunoelectrophoretic analysis of the glycoproteins and produced 5 major immunoprecipitates. The glycoprotein nature of the immunoprecipitates was shown by their susceptibility to neuraminidase. Crossed immunoelectrophoresis was used to examine the lectin binding specificity of isolated epidermal plasma membrane glycoproteins. The immunoprecipitation patterns were affected strongly by Ricinus communis agglutinin (RCA), moderately by wheatgerm agglutinin (WGA), and weakly by soybean agglutinin (SBA). Peanut agglutinin (PNA), Dolichos biflorus agglutinin (DBA), and Ulex europaeus agglutinin (UEA) had little effect on the immunoprecipitation patterns, indicating little interaction between epidermal plasma membrane glycoprotein and these lectins. Other glycoproteins and/or glycolipids must therefore be responsible for the binding of these lectins by epidermal cells.

Distribution of carbohydrate residues in normal skin

Sections of biopsies of normal skin obtained from 11 individuals were incubated with 8 lectins using an avidin-biotin complex (ABC). All sections when incubated with the appropriate lectin showed the presence of the following carbohydrate residues: L-fucose, beta-(1-4)-D-GlcNAc)2 (N-acetylglucosamine), acetylneuraminic acid, Gal-beta-(1-3)-GalNAc (N-acetyl-galactosamine), beta-D-galactose, alpha-D-glucose, and alpha-D-mannose. In addition, sections of individuals with blood group A showed alpha-D-GalNAc and sections of individuals with blood group B showed alpha-D-galactose. In the stratum (str.) basale, carbohydrates were present in small quantities, but as the cells matured and moved upward, the incorporation of carbohydrates into the cell membranes increased considerably. In the str. granulosum, lectin reactivity was absent in many sections, probably due to masking by phospholipids. The dark cells in the eccrine glands showed reactivity with all lectins except in the one nonsecretor with blood group A1, whose dark cells showed no L-fucose and alpha-D-GalNAc. The endothelial cells of the blood vessels showed lectin reactivity except when incubated with concanavalin A. The sebaceous glands showed both cytoplasmic and membrane staining when incubated with various lectins.

Epidermal fucosylation of cell surface glycoprotein

When Ulex europeus agglutinin I (UEA) conjugated with fluorescein isothiocyanate is applied to tissue sections from the cutaneous epidermis of the newborn rat, the lectin binds to the surfaces of cells in the layer immediately above the basal layer but not to the cells in the basal layer itself. The latter cells bind the isolectin I-B4, from Griffonia simplicifolia (GS I-B4). The addition of a fucosyl residue to the oligosaccharide of the glycoprotein found on the surface of the basal cell can account for the change in lectin-binding specificity which occurs as the basal cell moves toward the cutaneous surface and becomes a spinous cell. The epidermis of the newborn rat has the necessary transferase to convert a glycoprotein with binding-specificity for GS I-B4 to binding specificity for UEA by adding a fucosyl residue from GDP-L-fucose.

Concanavalin A binding glycoprotein in human stratum corneum

A mannose-containing 40K glycoprotein has been identified in the stratum corneum of normal human epidermis. It is apparently membrane-bound and in the intact epidermis it is inaccessible to either concanavalin A or to trypsin. After it is detergent-solubilized, it can be labeled with concanavalin A or destroyed with trypsin. There is little or none of this glycoprotein in the viable cells of the epidermis.

The binding of Helix pomatia and Ulex europeus agglutinins to normal and psoriatic skin

We have compared the staining patterns of Ulex europeus agglutinin (UEA) I-FITC and Helix pomatia agglutinin (HPA)-FITC on normal and psoriatic epidermis in order to follow the production of the binding sites as a function of maturation. We have further characterized them with respect to solvent extraction and enzyme digestion. The bandlike pattern of membrane staining by UEA I in the upper spinous and granular layer cells of normal epidermis is lost in psoriasis. Instead there is a fainter cytoplasmic staining which is largely sensitive to chloroform/methanol extraction, and thus presumably is glycolipid in nature. Epidermal binding of HPA to normal skin sections is mainly seen in cell membranes. It spares the basal layer and then increases from the suprabasal region to the granular layer. HPA staining in the spinous layer is destroyed by extraction with Triton X-100. In contrast, binding to the membranes of cells in psoriatic epidermis is triton-resistant. The result indicates the production of a component early in the maturation pathway which has no counterpart in normal skin. HPA binding to the spinous cells of symptomless skin from psoriatic patients shows decreased sensitivity to Triton X-100 by comparison with normal. The results are discussed in terms of changes in the pathway of keratinocyte maturation in psoriasis.

Histochemical studies of lectin binding patterns in keratinized lesions, including malignancy

Histochemical detection of lectin binding was carried out using the HRP-conjugated lectin method in hyperkeratinized lesions including leukoplakia, carcinoma in situ, Paget's disease, keratoacanthoma, and condyloma acuminatum. The lectins used for demonstrating sugar residues were: Con A (hexose), PNA and RCA-1 (Gal), DBA and SBA (GalNAc), UEA -1 (Fuc), and WGA (GlcNAc). Lectin binding in normal squamous epithelium showed regional distribution patterns of keratinized, spinous and basal layer types. Histochemical localization of lectin binding was generally at the cellular surface and in the intercellular substance and sometimes in the cytoplasm of normal epithelial cells. Dysplastic cells or carcinoma cell, in contrast, displayed a loss of cellular surface and intercellular staining. Paget's cells were devoid of lectin staining. In keratoacanthoma and condyloma specimens, spinous cells, which were PAS-positive, showed an intense PA/Con A-HRP staining and moderate binding by other lectins, which was somewhat decreased when compared with that in the surrounding intact epithelium. The cytochemical distribution of epithelial lectin binding might be indicative of the expression of normal stratification and keratinocytic differentiation , and the disappearance of this typical epithelial pattern may suggest severe dysplasia and malignancy.

Concanavalin A distinguishes among diseases of altered epidermal differentiation

Mannose-containing of glycoproteins from lesional tissue of several diseases of aberrant epidermal differentiation (palmar-plantar keratoderma, pachyonychia congenita, psoriasis, and epidermolytic hyperkeratosis) were analyzed by overlaying iodinated concanavalin A onto molecules separated by polyacrylamide gel electrophoresis. Gel autoradiograms showed that biopsy samples from patients with the same disease were very similar. The radioactivity profiles were different for each disease and were distinguishable from each other and from normal epidermis and callus. The resolution and sensitivity of this technique may be of diagnostic significance.

Subsets of epidermal Langerhans cells as defined by lectin binding profiles

In this study we characterize the cell surface glycoconjugate moieties of strain 2 guinea pig epidermal Langerhans cells (LC) in single cell suspension by using a battery of 17 fluorescent lectins. All LC displayed binding sites for concanavalin A, succinylated concanavalin A, Lens culinaris agglutinin, Pisum sativum agglutinin, wheat germ agglutinin, succinylated wheat germ agglutinin, Griffonia simplicifolia agglutinin I, Ricinus communis agglutinin I, Phaseolus vulgaris E agglutinin, and Phaseolus vulgaris L agglutinin, but failed to bind Sophora japonica agglutinin (SJA), Dolichos biflorus agglutinin (DBA), and Ulex europaeus agglutinin I (UEA I). Neuraminidase pretreatment rendered LC reactive for SJA, but not for DBA and UEA I. The binding profiles of certain lectins point to the existence of LC subpopulations in that Griffonia simplicifolia I-B4 isolectin, peanut agglutinin (PNA), Helix pomatia agglutinin, and soybean agglutinin bound to only 80% (range 70-90%) of Ia-positive epidermal cells; binding sites for these lectins on primarily unreactive Ia-positive cells were unmasked when epidermal cells were treated with neuraminidase prior to lectin labeling. Ultrastructural PNA labeling studies revealed that the vast majority of Birbeck granule-containing LC displayed PNA binding sites, whereas indeterminate cells were consistently PNA-negative. Identification of carbohydrate configurations expressed on LC surfaces by lectin binding may provide a clue for the elucidation of the mechanisms of established LC functions and possibly the discovery of as yet unknown properties of this cell type.

Involucrin and other markers of keratinocyte terminal differentiation

Human epidermal keratinocytes in culture form stratified colonies that retain many of the properties of intact epidermis. Mitosis is restricted to the basal layer, and cells that leave it undergo terminal differentiation, increasing in size and synthesizing a range of specialized molecules as they pass through the different cell layers. One useful marker for an early stage in the pathway of terminal differentiation is involucrin, a soluble protein precursor of the cross-linked envelope. Involucrin is synthesized after keratinocytes have left the basal layer and begun to enlarge, but some time before the onset of envelope cross-linking, which occurs only in the outermost cell layers. Small, involucrin-negative cells can be isolated and cultured in medium containing a low concentration of calcium ions, to prevent stratification, but not cell division and enlargement. Under these conditions, involucrin synthesis is initiated by some cells in the monolayer, indicating that attainment of a suprabasal position is not required for this step in terminal differentiation. Furthermore, if the level of calcium is raised to induce stratification, involucrin-positive cells are selectively expelled from the basal layer. This suggests that migration from the basal layer may be a consequence, not a cause, of terminal differentiation. Changes in cell-surface properties during terminal differentiation might explain the observed sorting out of involucrin-positive and -negative cells. We have therefore investigated lectin binding to different cell layers in natural and cultured human epidermis. Some lectins bind only to nonbasal keratinocytes, and the binding of peanut agglutinin, in particular, shows interesting correlations with involucrin expression, both in stratified colonies and in monolayers.

Modification of cell surface glycoprotein: addition of fucosyl residues during epidermal differentiation

When cutaneous sections from the newborn rat were treated with alpha-fucosidase, Ulex europeus agglutinin I (UEA) binding to the cell surface of the differentiated cells in the epidermis was diminished and there was an appearance in these cell layers of binding by Bandeiraea simplicifolia I-B4 lectin (BS I-B4), which normally is specific for the basal cells. A similar treatment with alpha-galactosidase resulted in a loss of BS I-B4 binding, but had no effect on UEA binding. Glycoproteins isolated from the membranes of epidermal cells showed a threefold increase in the ratio of binding to UEA versus BS I-B4 affinity columns as the proteins were derived from the more differentiated cell populations. These data suggest that alpha-fucosyl residues are added to the glycoproteins on the cell surfaces of differentiated cells, thus blocking alpha-galactosyl residues and changing the lectin binding specificity as epidermal cells move out of the basal cell layer.

Studies of lectin binding to normal and neoplastic lymphoid tissues. I. Normal nodes and Hodgkin's disease

Lectins are proteins which have the ability to interact specifically with carbohydrate residues of glycoproteins and other glycoconjugates. The staining patterns of 10 fluorescein conjugated lectins (F-Con A, F-LCA, F-RCA, F-WGA, F-PHA, F-PWM, F-LTA, F-SBA, F-PNA, F-DB) and a protease inhibitor (F-LA) have been studied in histological sections of 11 normal or reactive lymph nodes and 6 nodes and one skin biopsy involved by Hodgkin's disease. On the basis of the patterns of lectin binding, and current knowledge of their saccharide specificities, we found that within germinal centres there is an orderly carbohydrate rich extracellular matrix which contains a higher concentration of GlcNAc and terminal Gal residues than the surface membranes of component cells. This suggests active secretion rather than simple membrane shedding, and it is possible that this pericellular domain plays a part in the regulation of the proliferative response, or controls migration of lymphocytes in and out of the germinal centre. Lectin binding in Reed-Sternberg cells suggests that the huge nucleoli contain glycoconjugates of diverse structure, which may be linked with their failure to undergo cytokinesis.

Concanavalin A binding glycoproteins of epidermal cells

The Concanavalin A reactive glycoproteins of epidermal cells were analyzed by the application of the iodinated lectin to molecules separated by SDS-PAGE. Normal epidermal cells were maintained as undifferentiated or differentiated by controlling the Ca++ concentration of the growth medium. Some 20 labeled bands could be resolved. Their relative intensities changed dramatically with the stage of differentiation. Fresh tissue gave a radioactive profile similar to that for cultured differentiated cells, except for evidence of damage from the techniques used to separate the epidermis from the dermis (the damage being progressively more severe going from heat to ammonium chloride to trypsin separation). The labeling patterns for three carcinogen-transformed cell lines were markedly different from those of the normal cells. The least tumorigenic cell line had a profile in many respects intermediate between those of the normal differentiated and undifferentiated cells, while the other 2 lines showed greater deviation.

Lectins as markers of human epidermal cell differentiation

The expression of sugar residues on human epidermal cells was investigated by means of lectin binding, as a way of determining membrane structural changes occurring during the differentiation of the epidermis. Fourteen lectins of different sugar specificity were conjugated with fluorescein isothiocyanate (FITC-lectins) and tested in fluorescence microscopy on frozen sections of normal human epidermis. In parallel, FITC-lectins were tested on psoriatic-involved epidermis to visualize differences in the expression of sugar residues that might occur during abnormal epidermal differentiation. No labelling could be obtained with lectins from Bandeira simplicifolia I, Dolichos biflorus, Limulus poyphemus, Tetragonolobus purpureas, Ulex europeus I, and Triticum vulgaris (group 1 lectins). A "pemphigus-like" intercellular labelling of the whole epidermis, except the stratum corneum, was obtained with lectins from Canavalia ensiformis. Maclura pomifera, Phaseolus vulgaris, and Ricinus communis I (group 2 lectins). A selective intercellular labelling of the stratum spinosum and the stratum granulosum was seen in normal epidermis with lectins from Arachis hypogaea, Glycine max, Helix pomatia, and Sophora japonica (group 3 lectins). In psoriatic epidermis, not only the basal cell layer, but also cells from the adjacent lower stratum spinosum were found to be negative, using FITC-lectins of group 3. These data indicate that the expression of lectin binding sites in normal epidermis differs according to the maturation of the cell from the basal cell to the more mature keratinocyte in the stratum granulosum. They suggest that lectins may be used as markers of epidermal cells in various stages of normal and abnormal differentiation.

Lectin binding to murine oral mucosa and skin

Carbohydrates on epithelial cell surfaces of oral mucosa and skin from various anatomical regions of C3H mice were demonstrated with fluoresceinated lectins. With an individual lectin, all tissues showed a similar pattern of binding: most lectins showed binding to the cell surfaces of all nucleated cell layers although that to basal cells was often weaker and was occasionally absent. The corneocytes did not typically bind lectins except that the follicular keratin of the tail showed a uniform and intense fluorescence with several lectins. Basement membrane bound all lectins. The results indicate that detectable changes occur in the cell-surface carbohydrate composition as cells differentiate but that cell-surface carbohydrates do not differ markedly from one region to the next. Lectin binding may provide a convenient method of detecting functional changes in normal cells and in cells which have undergone experimental or pathological changes.

Ultrastructural and biochemical identification of Con A receptors in the desmosome

Correlated ultrastructural and biochemical methods were used to identify and localize Concanavalin A (Con A) receptors in the desmosomes of bovine epidermis. Specific carbohydrate residues were labeled with ferritin-Con A in thin sections of tissue embedded in a hydrophilic resin. Quantitative mapping of ferritin distribution in labeled desmosomes revealed that Con A receptors are localized in the intercellular zone and concentrated along the desmosomal midline or central dense stratum. Labeling was almost entirely absent when sections were treated with ferritin-Con A in the presence of 0.1 M alpha-methyl mannoside, a hapten-inhibitor of Con A. "Whole" desmosomes and desmosomal intercellular regions (desmosomal "cores") were purified from bovine muzzle epidermis. Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis reveals a limited number of major desmosomal protein constituents. Certain of these are glycoproteins and are greatly enriched in the core fraction. Almost all the desmosomal glycoproteins are intensely labeled when electrophoretic gels of whole desmosome or core fractions are exposed to fluorescent Concanavalin A.

The production of antibodies to cell membranes of squamous epithelium by the use of aldehyde-induced membrane vesicles

A new method for the isolation of plasma membrane residues which can be used to raise antibodies to oral epithelial cell membranes is described. Plasma membrane vesicles were formed on the cell surfaces of confluent rat oral epithelial cell cultures by exposing the cells in situ to 100 mM freshly prepared formaldehyde. The vesicles formed 10--15 min. after exposure and were released into the medium. The vesicles, 1--10 micrometers in diameter, were sedimented by centrifugation at 30,000 g for 20 min. Antibodies to vesicles were raised in rabbits and used in an indirect immunofluorescence and immunoperoxidase staining technique. In rat and human oral epithelium they stained cell membranes in the basal and spinous cell layers. No cytoplasmic staining was seen in the epithelium. Staining of squamous epithelium from the human uterine cervix, rat and human skin and guinea pig lip was negative.

Differential lectin binding to cellular membranes in the epidermis of the newborn rat

Three fluorescein-labeled lectins have been shown to exhibit specificity for the surface of cells in different layers of the epidermis in the newborn rat. An isolectin from seeds of Bandeiraea simplicifolia with specificity for alpha-D-galactosyl end groups labeled the basal and lower spinous cells; a lectin from Ulex europaeus exhibiting specificity for alpha-L-fucosyl units outlines the surface of spinous cells, and a second lectin from B. simplicifolia, with specificity for N-acetyl-D-glucosamine, labels the cornified cells. Appropriate blocking experiments have confirmed the specific nature of the binding.

Dynamic redistribution of concanavalin A binding sites on isolated guinea pig keratinocytes

Modifications in the distribution of the binding sites for concanavalin A (Con A) were studied on trypsin isolated living guinea pig keratinocytes. Fluorescein-labelled Con A was used and the in vitro procedure has included short-term cultures, experiments at 37 degrees C and 4 degrees C, the study of colchicine and vincaleucoblastine effects. It was possible to induce different patterns of staining corresponding to distinct redistribution of Con A binding sites; the distinct redistribution was correlated to the effects of Con A, colchicine and vincaleucoblastine. These findings demonstrated that the system used was appropriate to the study of some dynamic events on the keratinocytes membranes.

Localization of specific carbohydrate configurations in human skin using fluorescein-labelled lectins

The binding of three fluorescein-labelled lectins by normal human skin has been studied. The patterns of bound fluorescence seen were characteristic for each lectin, indicating that saccharide residues were available for lectin localization in the skin. Concanavalin A (glucose and mannose specific) and ricin 120 (galactose specific) presented similar patterns of localization of fluorescence in the epidermis and dermis. Both lectins presented a continuous band at the dermo--epidermal junction, but with concanavalin A the band was broader, while with ricin 120 the junctional band was thinner and more closely associated with the epidermal interface. With the peanut lectin (galactose specific) fluorescence outlined the periphery of the keratinocytes in the upper Malpighian and granular cell layers only; no junctional band was seen and the dermal appendages and collagen did not fluoresce. The stratum corneum did not fluoresce with any of the lectins studied.

Partial purification of pemphigus-related epidermal antigens

Epidermal antigens partially purified by either isoelectric focusing (the pH 5.2 peak) or concanavalin A (Con A) affinity chromatography react with Con A in tube precipitation reactions. Bands of identity between crude skin antigens, the Con A affinity antigens eluted with alpha-methyl glucoside and the pH 5.2 peak are formed in Ouchterlony gel with rabbit antisera (Rab) to the pH 5.2 antigen. Absorption of Rab or pemphigus antibodies (Pab) with A+ erythrocytes does not affect complement fixation reactions of Rab with the skin antigen nor abolish the ability of Pab to interact with the intercellular cement. The pH 5.2 epidermal antigens react weakly with Pab in tube precipitation reactions and only weakly, if at all, to inhibit Pab reactions in the region of the intercellular cement. High concentrations of Con A inhibit the Pab, peroxidase-anti-IgG tissue reaction whereas the converse inhibition does not occur. Simultaneous use of both Pab and Con A-perodixase reactions at Con A concentrations which do not inhibit Pab, causes enhanced tissue peroxidase reactions in the region of the intercellular cement. These preliminary data indicate that the Pab and Con A-reacting sites are localized on different molecules or antigenic determinants in the intercellular cement. They exclude the possibility that A-blood substances are involved in either site.

Histochemistry of the intercellular substance of the normal and psoriatic human epidermis

The intercellular substance of skin samples obtained from normal subjects and from psoriatic patients has been studied with histochemical methods for carbohydrate containing substances and checked with enzymatic extractions. The surface coat which makes up most of the intercellular substance was stained with colloidal iron and with Alcian Blue solutions containing up to 0.20 M magnesium chloride; the stainings were heavily affected by the previous treatment of the sections with testicular hyaluronidase, but not with neuraminidase. The staining of the intercellular substance with Alcian Blue solutions containing up to 0.20 M magnesium chloride and the action of the hyaluronidase gives strength to the hypothesis that hyaluronic acid is contained in the substance. In the skin of psoriatic patients intercellular spaces wider than in normal skin and a reduced surface coat, particularly in the higher layers, has been observed.

Concanavalin A and ricinus communis receptor sites in normal human oral mucosa

Fluorescein conjugates of concanavalin A (Con-A) and Ricinus communis fraction 120 (RCA120) were shown to bind to the cell surfaces of basal and spinous cell layers in oral buccal mucosa. Palatal epithelium showed distinct binding to basal and spinous cells; cell membranes in the granular layer occasionally bound Con-A and always RCA120. The ultrastructural localization of Con-A binding sites on exfoliated buccal cells was detected by the Con-A peroxidase staining method. The Con-A receptors were seen on the cell surface in association with the outer leaflet of the plasma membrane. The reaction products appeared as a homogeneous, electron-dense layer containing irregularly distributed globules.

Degranulation of dermal mast cells: effects of fixation and of antidromic nervous impulses on two histochemically identified cell-types

Two types of mast cell can be identified histochemically in the dermis of the rat's external ear. One type is recognized by the binding of concanavalin A (con A) to the cytoplasmic granules (con A-positive cells) while in the other type (con A-negative cells), the granules do not bind con A. The granules in both types are stained metachromatically by toluidine blue. Antidromic stimulation of the great auricular nerve for 2 min results in an increased proportion of degranulating mast cells in the auricular dermis and both types of cell are affected to an approximately equal extent. In discussion of this observation, it is argued that both the con A-positive and the con A-negative mast cells are probably involved in the mediation of vasodilatation due to axon reflexes in injured skin. The proportions of degranulating mast cells determined in histological preparations varied with the fixatives (Carnoy and glutaraldehyde-formaldehyde) used, but the increased degranulation due to antidromic nervous stimulation could be detected after either fixation.

Inhibition of the in vivo effects of concanavalin-A on mammalian epidermis by alpha-methyl-D-glucopyranoside

Concanavalin-A (Con-A) injected intradermally into newborn rats produces inhibition of granular-cell formation, accumulation of spinous cells, glycogen deposition, and a decrease followed by an increase in the number of basal cells in DNA synthesis. These changes were maximal with a dose of 0.1 mg Con-A, although 0.005, 0.01, and 0.05 mg caused some epidermal changes. The Con-A effects were partially blocked when 0.1 ml of 0.3 or 0.1 M alpha-methyl-D-glucopyranoside (alphaMG) solution was injected 2 hr after 0.1 mg Con-A and completely inhibited by injection of 0.1 ml of 3.0 M alphaMG solution. The inhibitory effects were not seen after injection of 0.1 ml of 3.0 M N-acetyl-galactosamine saline solution, or 0.1 ml normal saline. Injection of alphaMG alone did not cause any changes in epidermal cells. These results indicate that specific sugar inhibits Con-A effects on mammalian epidermis in vivo.

Localization of alpha-D-glucosyl and alpha-D-mannosyl groups of mucosubstances with concanavalin A and horseradish peroxidase

Concanavalin A is a lectin which is known to bind specifically to alpha-D-glucosyl and alpha-D-mannosyl groups in the mucosubstances of mammalian tissues. The lectin molecule is bivalent; after its attachment to mucosubstances present in a histological specimen it can also bind horseradish peroxidase, a mannose-containing glycoprotein. The attached peroxidase may then be visualized by virtue of its histochemically demonstrable enzymatic activity. Other investigators have utilized this principle in the electron microscopic localization of cell-surface carbohydrates. A histochemical technique for light microscopy is described here, along with three control procedures which establish the specificity of the method. The technique is somewhat more sensitive than earlier ones in which fluorescent-labelled concanavalin A was used, and has the additional advantages that all the required reagents are commercially available and that sacilities for fluorescence microscopy are not needed.

The interaction of Concanavalin A and the surface coat of stratified squamous epithelium

The interaction of Concanavalin A (Con A) and the surface membranes of the epithelial cells of human oral mucosa, epidermis and guinea-pig lip was studied. Two methods were used: fluorescent Con A and Con A in combination with horse radish peroxidase. With both methods the surface coat of epithelial cells was stained. The specificity of the staining methods could be demonstrated. The interaction between pemphigus antibodies and the surface membranes of epithelial cells could be blocked by Con A.