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

Hypoxic pre-conditioning increases the infiltration of endothelial cells into scaffolds for dermal regeneration pre-seeded with mesenchymal stem cells

Many therapies using mesenchymal stem cells (MSC) rely on their ability to produce and release paracrine signals with chemotactic and pro-angiogenic activity. These characteristics, however, are mostly studied under standard in vitro culture conditions. In contrast, various novel cell-based therapies imply pre-seeding MSC into bio-artificial scaffolds. Here we describe human bone marrow-derived MSC seeded in Integra matrices, a common type of scaffold for dermal regeneration (SDR). We show and measured the distribution of MSC within the SDR, where cells clearly establish physical interactions with the scaffold, exhibiting constant metabolic activity for at least 15 days. In the SDR, MSC secrete VEGF and SDF-1α and induce transwell migration of CD34⁺ hematopoietic/endothelial progenitor cells, which is inhibited in the presence of a CXCR4/SDF-1α antagonist. MSC in SDR respond to hypoxia by altering levels of angiogenic signals such as Angiogenin, Serpin-1, uPA, and IL-8. Finally, we show that MSC-containing SDR that have been pre-incubated in hypoxia show higher infiltration of endothelial cells after implantation into immune deficient mice. Our data show that MSC are fully functional ex vivo when implanted into SDR. In addition, our results strongly support the notion of hypoxic pre-conditioning MSC-containing SDR, in order to promote angiogenesis in the wounds.

Dynamic changes in cell-surface expression of mannose in the oral epithelium during the development of graft-versus-host disease of the oral mucosa in rats

Background

The role of cell-surface glycoconjugates in oral mucosal graft-versus-host disease (GVHD) is still unclear, even though molecular changes in the oral epithelium are essential for the pathogenesis of these lesions. In this study, we investigated changes in the binding of mannose (Man)-specific Lens culinaris lectin (LCA) in the oral mucosa of rats with GVHD.

Methods

Lewis rat spleen cells were injected into (Lewis x Brown Norway) F₁ rats to induce systemic GVHD, including oral mucosal lesions. Tongue and spleen samples were evaluated using lectin histochemistry, immunohistochemistry, Western blotting, transwell migration assays and Stamper-Woodruff binding assays.

Results

Binding of Man-specific LCA expanded to the epithelial layers of the tongue in GVHD-rats. An expansion of LCA binding was related to the increased expression of mannosyltransferase in the oral mucosa. CD8⁺ cells, effector cells of oral mucosal GVHD, expressed mannose-binding protein (MBP) and migrated to the medium containing Man in the transwell migration assay. Adherence of CD8⁺ cells to the oral epithelium could be inhibited by pretreating CD8⁺ cells with MBP antibody and/or by pretreating sections with Man-specific LCA.

Conclusions

Increased expression of Man on keratinocytes leads to the migration and/or adhesion of CD8⁺ cells in the surface epithelium, which is mediated in part by the MBP/Man-binding pathway during the development of oral mucosal GVHD.

The isolectin IB4 binds RET receptor tyrosine kinase in microglia

Ret receptor tyrosine kinase is the signaling component of the receptor complex for the family ligands of the glial cell line-derived neurotrophic factor (GDNF). Ret is involved in the development of enteric nervous system, of sympathetic, parasympathetic, motor and sensory neurons, and it is necessary for the post-natal maintenance of dopaminergic neurons. Ret expression has been as well demonstrated on microglia and several evidence indicate that GDNF regulates not only neuronal survival and maturation but also certain functions of microglia in the brain. Here, we demonstrated that the plant lectin Griffonia (Bandeiraea) simplicifolia lectin I, isolectin B4 (IB4), commonly used as a microglial marker in the brain, binds to the glycosylated extracellular domain of Ret on the surface of living NIH3T3 fibroblasts cells stably transfected with Ret as well as in adult rat brain as revealed by immunoblotting. Furthermore, confocal immunofluorescence analysis demonstrated a clear overlap in staining between pRet and IB4 in primary microglia cultures as well as in adult rat sections obtained from control or post-ischemic brain after permanent middle artery occlusion (pMCAO). Interestingly, IB4 staining identified activated or ameboid Ret-expressing microglia under ischemic conditions. Collectively, our data indicate Ret receptor as one of the IB4-reactive glycoconjugate accounting for the IB4 stain in microglia under physiological and ischemic conditions.

Mucin 21 in esophageal squamous epithelia and carcinomas: analysis with glycoform-specific monoclonal antibodies

Monoclonal antibodies (mAbs) against mucin 21 (MUC21), a human counterpart of mouse epiglycanin/Muc21, were prepared using human embryonic kidney 293 cells transfected with MUC21 as the immunogen. The specificity of these mAbs was examined by flow cytometry, immunoprecipitation and western blotting focusing on the differential glycosylation of MUC21 expressed in variant Chinese hamster ovary (CHO) cells (ldlD cells and Lec2 cells) and CHO-K1 cells. One of these mAbs, heM21D, bound to both the unmodified core polypeptide of MUC21 and MUC21 attached with N-acetylgalactosamine (Tn-MUC21). Six antibodies, including mAb heM21C, bound to MUC21 with Tn, T or sialyl-T epitopes but not the unmodified core polypeptide of MUC21. Esophageal squamous carcinomas and adjacent squamous epithelia were immunohistochemically examined for the binding of these mAbs. MUC21 was expressed in esophageal squamous epithelial cells, and its O-glycan extended forms were observed in the luminal portions of squamous epithelia. As revealed by the binding of mAb heM21D and the absence of reactivity with mAb heM21C, esophageal squamous carcinoma cells produce MUC21 without the attachment of O-glycans. This is the first report to show that there is a change in the glycoform of MUC21 that can be used to differentiate between squamous epithelia and squamous carcinoma of the esophagus. Thus, these antibodies represent a useful tool to characterize squamous epithelial differentiation and carcinogenesis.

A phenotypically restricted set of primary afferent nerve fibers innervate the bone versus skin: therapeutic opportunity for treating skeletal pain

Although musculoskeletal pain is one of the most common causes of chronic pain and physical disability in both developing and developed countries, relatively little is known about the nerve fibers and mechanisms that drive skeletal pain. Small diameter sensory nerve fibers, most of which are C-fiber nociceptors, can be separated into two broad populations: the peptide-rich and peptide-poor nerve fibers. Peptide-rich nerve fibers express substance P (SP) and calcitonin gene-related peptide (CGRP). In contrast, the peptide-poor nerve fibers bind to isolectin B4 (IB(4)) and express the purinergic receptor P(2)X(3) and Mas-related G protein-coupled receptor member d (Mrgprd). In the present report, we used mice in which the Mrgprd(+) nerve fibers express genetically encoded axonal tracers to determine the peptide-rich and peptide-poor sensory nerve fibers that innervate the glabrous skin of the hindpaw as compared to the bone marrow, mineralized bone and periosteum of the femur. Whereas the skin is richly innervated by CGRP(+), SP(+), P(2)X(3)(+) and Mrgprd(+) sensory nerve fibers, the bone marrow, mineralized bone and periosteum receive a significant innervation by SP(+) and CGRP(+), but not Mrgprd(+) and P(2)X(3)(+) nerve fibers. This lack of redundancy in the populations of C-fibers that innervate the bone may present a unique therapeutic opportunity for targeting skeletal pain as the peptide-rich and peptide-poor sensory nerve fibers generally express a different repertoire of receptors and channels to detect noxious stimuli. Thus, therapies that target the specific types of C-nerve fibers that innervate the bone may be uniquely effective in attenuating skeletal pain as compared to skin pain.

Alterations in PNA binding of keratinocytes in oral keratosis

Changes in the expression of peanut lectin (PNA) were examined in keratinocytes of oral keratosis showing a mixture of hyperortho- and hyperparakeratinized epithelium. In the hyperorthokeratinized epithelium, which was reacted with anti-filaggrin antibody in both granular and cornified cells, PNA bound to the surface of keratinocytes from the spinous layer to the granular layer. Neither anti-filaggrin nor PNA reactions were detected in keratinocytes of the hyperparakeratinized epithelium. After neuraminidase pretreatment, however, PNA staining appeared in all cells, except cornified cells, of both hyperortho- and hyperparakeratinized epithelia. These findings suggest that PNA-binding epitopes in keratinocytes were modified by sialic acid during the hyperparakeratotic process of oral keratosis.

Griffonia simplicifolia isolectin B4 identifies a specific subpopulation of angiogenic blood vessels following contusive spinal cord injury in the adult mouse

After traumatic spinal cord injury (SCI), disruption and plasticity of the microvasculature within injured spinal tissue contribute to the pathological cascades associated with the evolution of both primary and secondary injury. Conversely, preserved vascular function most likely results in tissue sparing and subsequent functional recovery. It has been difficult to identify subclasses of damaged or regenerating blood vessels at the cellular level. Here, adult mice received a single intravenous injection of the Griffonia simplicifolia isolectin B4 (IB4) at 1-28 days following a moderate thoracic (T9) contusion. Vascular binding of IB4 was maximally observed 7 days following injury, a time associated with multiple pathologic aspects of the intrinsic adaptive angiogenesis, with numbers of IB4 vascular profiles decreasing by 21 days postinjury. Quantitative assessment of IB4 binding shows that it occurs within the evolving lesion epicenter, with affected vessels expressing a temporally specific dysfunctional tight junctional phenotype as assessed by occludin, claudin-5, and ZO-1 immunoreactivities. Taken together, these results demonstrate that intravascular lectin delivery following SCI is a useful approach not only for observing the functional status of neovascular formation but also for definitively identifying specific subpopulations of reactive spinal microvascular elements.

Lectin histochemistry on the dorsal epidermis of the Breton dog

Expression of sugar residues and the nature of oligosaccharide linkage during keratinocyte maturation in the epidermis of the Breton dog were studied with the use of lectin histochemistry. Thirteen lectins were used. Labelling was not observed with GSA I-B4, GSA II, UEA-I, and LTA. The cytoplasm of keratinocytes reacted with PNA, HPA, Con A, and WGA from the basal layer to the granular layer. PNA and Con A showed highest reactivity in the granular cell layer. The cell surface showed increased reactivity with PNA, HPA, and WGA with maturation of keratinocytes. KOH-neuraminidase treatment (KOH-Neu) increased PNA and RCA120 staining during keratinocyte differentiation thus indicating an increase in oligosaccharides terminating with sialic acid-Galbeta(1,3)GalNAc and sialic acid-Galbeta(1,4)GlcNAc, respectively. Labelling of the glycocalyx of basal and spinous keratinocytes with SNA and MAA revealed terminal Neu5acalpha(2,6)Gal/GalNAc and Neu5acalpha(2,3)Galbeta(1,4)GlcNAc. KOH-Neu-DBA showed oligosaccharides terminating with sialic acid-GalNAcalpha(1,3)GalNAc in the spinous and granular layers. A selective glycocalyx labelling of granular keratinocytes was observed with DBA and SBA. Reactions with MAA, PNA, DBA, RCA120, SBA, HPA, and WGA disappeared after the beta-elimination reaction. Our findings indicate that Breton dog epidermis contains more O-linked than N-linked oligosaccharides and confirm that different subpopulations of keratinocytes can be distinguished by lectin histochemistry.

Quantitative study of changes in intestinal morphology and mucus gel on total parenteral nutrition in rats

Quantification of changes in gastrointestinal morphology and mucus gel has been difficult to study. In the present study, we investigated changes in rat intestine under total parenteral nutrition (TPN) using fluoresceinated lectin staining and image analysis. Wistar rats (n = 34) were divided into two groups: one group received TPN for 2 weeks, and a control group received standard rat chow and water ad libitum for the same period. A 1-cm segment of distal ileum was removed and cut into cross sections. Sections were stained with hematoxylin and eosin, and to stain the mucus, periodic acid-Schiff (PAS), alcian blue (AB), and fluoresceinated lectin, that is, FITC-labeled Ulex europaeus agglutinin I (FITC-UEA-I), were used. Light microscope images were stored in a personal computer and analyzed using image analysis. We measured perimeter length, mucosal thickness, villus area, villus surface area index, mucus stain-positive area, mucosal area ratio, and mucosal surface area ratio. Perimeter length, mucosal thickness, villus area, and villus surface area index in the TPN group were significantly less than those in the control group (P < 0.001 for each parameter). In all mucus stainings, the stain-positive area in the TPN group was significantly less than that in the control group. However, there were no significant differences in mucosal area or mucosal surface area ratios between the two groups. The FITC-UEA-I-positive area was significantly greater than the PAS- or and AB-positive area. There were significant positive correlations between the FITC-UEA-I-positive area and both the PAS-positive and AB-positive areas. TPN for 2 weeks promoted intestinal atrophy and decreased absolute quantity of mucus gel. We successfully introduced the FITC-UEA-I staining method to evaluate changes in mucus gel.

Lectin binding patterns in amphibian skin epithelium

Seven lectins (PNA, DBA, WGA, UEA-I, RCA, SBA, Con A) were used to localize glycoconjugates in the skin of 10 species of Amphibia, 7 anurans (Bufo marinus, Bufo bufo, Rana ridibunda, Rana pipiens, Hyla arborea, Pelobates syriacus and Xenopus laevis) and 3 urodeles (Salamandra salamandra, Triturus vulgaris and Ambystoma mexicanum). It was found that every lectin has a specific binding pattern in the skin of each species. No common pattern could be established, either among frogs or toads, nor for a particular lectin. Each lectin bound specifically and selectively to a particular epithelial component, which differed from one species to the other. A number of lectins showed selective binding to mitochondria-rich cells, but, again, a pattern in positivity could not be found. It is concluded that lectin histochemistry does correlate with cellular function. Our data can be applied in studies of epithelium and skin development, and of changes that occur during adaptation to the environment by amphibian species.

Lectin histochemistry of dorsal skin of Wistar-derived hypotrichotic WBN/Ila-Ht rats

A lectin histochemical study was carried out on the dorsal skin of Wistar-derived hypotrichotic WBN/Ila-Ht rats (HtRs) and Wistar rats (WRs) at 3, 7 and 24 weeks of age to clarify the lectinhistochemical characteristics of the skin during their development. The lectins examined were Concanavalia ensiformis (Con A), Dolichos biflorus agglutinin (DBA), Griffonia simpliciolia (GS-I), Helix pomatia agglutinin (HPA), Arachis hypogaea (PNA), Glycine maximus agglutinin (SBA), Ulex europeus agglutinin (UEA-I) and Triticum vulgaris agglutinin (WGA). None of the nucleated cell layers of the epidermis had DBA-binding sites, but they were all stained intensely with HPA and weakly with Con A irrespective of the strain and age of the rats. As to the other 5 lectins, the intensity of binding activity was generally weaker in HtRs than in WRs and at 3 weeks of age than at 7 or 24 weeks of age, respectively. Among them, UEA-I mainly bound to the spinous cell layer but not to the basal cell layer, suggesting that alpha-L-fucose would be expressed on the cell surface according to the differentiation of keratinocytes. In addition, GS-I, HPA and UEA-I bound to the hair follicle epithelium and many lectins stained sebaceous gland epithelial cells. In conclusion, except for the binding intensity of some lectins, there were no specific differences between HtRs and Wrs in the lectinhistochemical characteristics of the dorsal skin epidermis. The present data on the rat skin would be useful from the viewpoint of comparative lectinhistochemistry.

Lectin binding characteristics of squamous cell carcinomas of the head and neck

Lectins are polyvalent proteins of non-immune origin with exquisite carbohydrate binding specificity making them ideal for investigation of cell surface glycoprotein and glycolipid antigens. We examined the cell surface lectin binding phenotypes of 20 UM-SCC squamous cell carcinoma cell lines established from 17 patients with head and neck cancers using a panel of fluorescein-conjugated lectins and inhibition by the appropriate monosaccharide to confirm specificity of using a panel of fluorescein-conjugated lectins and inhibition by the appropriate monosaccharide to confirm specificity of binding. Conconavalin A (Con A) from Canavalia ensiformis and the peanut agglutinin (PNA) from Arachis hypogaea bound all SCC cell lines tested and wheat germ agglutinin (WGA) from Triticum vulgaris bound to 12 of 13 tumor cell lines. The blood group O specific lectin UEA 1 from Ulex europeus also bound to all cell lines regardless of the donor blood type. Lectins of Dolichos biflorus (DBA) and Griffonia simplicifolia (GS I-B4 or BSA I-B4) with binding specificity for glycoproteins associated with blood group A and B respectively, had reactivity that did not directly correlate with blood group antigen expression. In contrast to the other lectins in our panel which exhibited broad reactivity with SCC antigens, the BSA-II lectin from Griffonia simplicfolia, (GS II or BSA II) which has sugar binding specificity for terminal non-reducing GlcNAc, did not bind to any of the screened cell lines. Our results demonstrate a common pattern of lectin-defined carbohydrate expression on the cell surface of squamous cell carcinomas of head and neck that appears promising in defining the malignant cellular phenotype. Lectin binding profile may be useful in differentiating benign from malignant histopathology.

Glycoconjugates and keratin 18 define subsets of taste cells

Sections of neonatal, normal adult and denervated adult rat tongue were examined with lectin histochemistry. Attention was focused upon intragemmal cells (cells within the taste bud) and the surrounding perigemmal cells. Informative staining patterns were observed with four of 12 lectins: Ulex europaeus (UEA-I), Bauhinia purpurea (BPA), Helix pomatia (HPA) and Lotus tetragonolobus (LTA) agglutinins. In normal adult tongues, BPA bound to those lingual epithelial cells lacking contact with the basal lamina. After they formed, vallate taste buds were laterally surrounded by distinctive BPA-positive cells. HPA reacted selectively with 28% and LTA with 23% of the intragemmal cells in vallate/foliate taste buds. In double-stained taste buds there was a statistically significant overlap of LTA-positive cells and keratin 18-positive cells. The overlap between HPA binding and keratin 18 was more marked: double-stained cells comprized 67% of all stained cells. During taste bud development in neonates keratin 18 synthesis preceded HPA binding. In contrast, during the replacement of adult taste cells, keratin 18 synthesis and HPA binding were generally concurrent. Keratin 18 and HPA probably identify the same subset of older taste receptor cells. HPA may bind to glycoconjugates on the surface of keratin 18-positive cells. In denervated adult tongue the loss of all UEA-I-positive or BPA-positive perigemmal cells suggests that perigemmal as well as intragemmal cells are nerve-dependent.

Glucosylceramides stimulate murine epidermal hyperproliferation

Hydrolysis of glucosylceramides (GlcCer) by beta-glucocerebrosidase generates ceramides, critical components of the epidermal permeability barrier. Ceramides also are involved in the regulation of cellular proliferation and differentiation in a variety of cell types. Whereas most studies have focused on ceramides and their sphingoid base metabolites as growth inhibitors, GlcCer apparently acts oppositely (i.e., as a mitogen). To determine whether enhancement of GlcCer content stimulates epidermal mitogenesis, we examined the response of hairless mouse epidermis to alterations in endogenous and/or exogenous GlcCer. Topical applications of conduritol B epoxide, a specific irreversible inhibitor of beta-glucocerebrosidase, increased epidermal GlcCer levels twofold, an alteration localized largely to the basal, proliferative cell layer (fourfold increase); and stimulated epidermal proliferation (2.3-fold elevation in [3H]thymidine incorporation; P < or = 0.001), localized autoradiographically again to the basal layer, and resulting in epidermal hyperplasia. Intracutaneous administration of GlcCer (2.0 mg) also stimulated epidermal DNA synthesis, while simultaneous treatment with conduritol B epoxide plus GlcCer resulted in an additive increase in DNA synthesis. These increases in epidermal proliferation could not be attributed either to altered epidermal permeability barrier function, or to nonspecific irritant effects, as determined by four separate criteria. These results strongly suggest that GlcCer directly stimulates epidermal mitogenesis.

Immunohistochemical study of cell proliferation and differentiation in epidermis of mice after administration of cholera toxin

Cholera toxin causes reversible epidermal hyperplasia. We observed maximal thickness of the epidermis on the fourth day after treatment and a return to pretreatment values by day 7. The increase in thickness occurred in the basal and intermediate layers, with these layers becoming two to three times thicker than those of normal epidermis. The time sequence of epidermal proliferation was studied using bromodeoxyuridine (BrdU) labelling. We observed a maximum number of labelled basal cells within the first 24 h. Only a few cells were labelled 7 days after toxin injection. Griffonia simplicifolia-IB4 (GSA-IB4), Ulex europaeus-I (UEA-I) and Griffonia simplicifolia-II (GSA-II) lectins were used for the analysis of epidermal cell differentiation in the tissue sections. To study keratinocyte differentiation, further immunological staining was performed using two anticytokeratin antibodies, PKK2 and PKK3 mouse monoclonal antibodies. From the immunocytochemical results, we conclude that synchronous differentiation of the epidermis occurs after cholera toxin administration.

Expression of "cell-type-specific" markers during rat tracheal epithelial regeneration

Previous studies showed that Griffonia simplicifolia I-isolectin B4 (GS I-B4) and monoclonal antibodies (mAbs) against keratin 14 labeled basal cells in the adult rat trachea while other mAbs specifically stained secretory and/or ciliated cells. We used these "cell-type-specific" markers to study cellular differentiation during tracheal epithelial regeneration. Denuded tracheal grafts were inoculated with rat tracheal epithelial cells and were implanted in syngeneic hosts. Marker expression was correlated with the appearance of morphologically defined cell types. At 4 days, the epithelium was squamoid, one to three cell layers thick, and was apparently composed of a single morphologic cell type. Because this cell did not exhibit distinguishing features of any mature tracheal cell, we provisionally termed it the "poorly differentiated cell" (PD cell). PD cells expressed keratin 14 and GS I-B4 binding sites; they contained glycogen and had lipid droplets but did not react with secretory or ciliated cell-specific mAbs. At 7 days, areas of the epithelium were pseudostratified and secretory cell-specific markers were present at the apex of differentiating columnar cells; ultrastructurally, these cells resembled secretory cells in adult tracheas. Simultaneously, a few preciliated and ciliated cells appeared that expressed a ciliated cell-specific epitope. No cells were observed coexpressing secretory and ciliated cell markers. Basal cells also became recognizable on day 7. These expressed keratin 14 and GS I-B4 binding sites throughout the study. Newly appearing secretory and ciliated cells also expressed these two markers initially but lost them gradually as the mucociliary epithelium matured. In the tracheal graft model of epithelial regeneration, the PD cells were pivotal intermediates from which all differentiated cells developed. Basal cells continued to express the same markers as PD cells, which were gradually lost in secretory and ciliated cells as they acquired new sets of specific epitopes.

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)

Properties of rat tracheal epithelial cells separated based on expression of cell surface alpha-galactosyl end groups

We used Griffonia (bandeiraea) simplicifolia I (GS I) lectin and flow cytometry to isolate subsets of rat tracheal epithelial cells based on the presence or absence of cell surface alpha-galactosyl end groups. These fractions were designated GS I-positive and -negative, respectively. Ninety-eight percent of the cells in the GS I-positive fraction expressed cell surface alpha-galactosyl end groups; 95% had immunocytochemically detectable keratin 14-related protein (a basal cell marker) and 98% lacked alcian blue-periodic acid-Schiff (AB-PAS)-stained cytoplasmic granules. More than 90% of the GS I-positive cells had a high nuclear-to-cytoplasm ratio, had tonofilaments, and lacked organelles characteristic of other differentiated cell types; they were thus classified as basal cells. In bioassays, the GS I-positive fraction had a colony-forming efficiency greater than or equal to that of native tracheal cell suspensions, and the cells were able to repopulate denuded tracheal grafts with ciliated, secretory, and basal cells. More than 99% of the cells in the GS I-negative fraction lacked cell surface alpha-galactosyl end groups, 98% did not stain for keratin 14-related protein, 54% had significant numbers of AB-PAS-stained cytoplasmic granules, and 16% were identified as ciliated cells. The GS I-negative fraction had a lower colony-forming efficiency than the GS I-positive fraction but, it too, was able to repopulate denuded tracheal grafts with a complete mucociliary epithelium. These results show that both GS I-positive and -negative cells had the potential to proliferate and differentiate into the major tracheal cell types.

Lectin histochemistry on squamous metaplasia in different epithelial tumors of dogs

Biotinylated lectins and avidin-biotin-peroxidase complex were used to study the correlation between cellular glycoconjugates' expression and squamous maturation in normal canine skin and in various epithelial neoplasms. Normal skin tissue was obtained from five, male, random-source dogs, 5 to 7 years old. The tumors tested, selected from the files of our Department, were fifteen squamous cell carcinomas from different tissue origin, five hepatoid perianal gland adenocarcinomas with squamous metaplasia, and fourteen solid mammary carcinomas with and without histologic evidence of squamous metaplasia. Except for mammary gland carcinomas, all tumors had been surgically excised from male dogs. Intermediate filament aggregation of twelve solid mammary gland carcinomas were studied electron microscopically. The basal and the lower spinous cells in normal skin and the less differentiated cells in squamous cell carcinomas stained moderately with Griffonia simplicifolia agglutinin-I. Spinous and granular cell layers stained strongly with Phytolacca americana mitogen and Arachis hypogaea agglutinin. Both lectins stained well-differentiated cells in squamous cell carcinomas. The electron microscopic study carried out in solid carcinomas of mammary glands revealed some relationship between the presence of intracytoplasmic tonofibrils and the binding of Griffonia simplicifolia agglutinin-I and Phytolacca americana mitogen to the tumors tested. Our results suggest that the glycosylation pattern occurring during normal keratinocyte differentiation is conserved in squamous cell carcinomas and that Griffonia simplicifolia agglutinin-I and Phytolacca americana mitogen may represent useful tools in distinguishing poorly differentiated squamous cell carcinomas from other poorly differentiated mammary epithelial tumors.

Subpopulations of primary adult murine epidermal basal cells sedimented on density gradients

Epidermal cells were harvested from the dorsal skin of adult mice by trypsinization and were sedimented through continuous density gradients of Percoll, formulated to separate basal cells of different buoyant density. Five fractions from the gradients were characterized with regard to the number of cells present, their viability and morphology and their basal origin. Suprabasal keratinocytes remained primarily at the top of the gradient; basal keratinocytes sedimented throughout. With increasing density, a relative enrichment was observed: (i) for [3H]-thymidine and [3H]-benzo[alpha]pyrene label-retaining (slowly cycling) keratinocytes; (ii) for keratinocytes that could proliferate in vitro in the continuous presence of 0.1 micrograms ml-1 of 12-O-tetradecanoylphorbol-13-acetate; (iii) for cells from untreated as well as initiated epidermis able to proliferate under conditions where calcium induces terminal differentiation; and (iv) for primary in vitro clonogenic keratinocytes from normal epidermis. The relative enrichment for epidermal basal cells having characteristics thought to be associated with immaturity and with the initiation and promotion of skin carcinogenesis suggests that density gradient sedimentation could be used in conjunction with other methods for the eventual purification of epidermal progenitors.

Glycoconjugate expression of cells of human anagen hair follicles during keratinization

Changes in the expression of glycoconjugates in cells of the inner root sheath (IRS) and outer root sheath (ORS) of human anagen hair follicles were investigated by lectin histochemistry. Concanavalin A (Con A) and Ricinus communis (RCA-I) stained hair follicle cells regardless of their differentiation stages. In IRS, Ulex europeaus-I (UEA-I) bound to the surface of the cells as soon as they were morphologically defined, and Glycine max (SBA) stained as their differentiation progressed. Innermost (IM) cells of ORS layers were reactive with UEA-I at the stage where Henle's cells were keratinized, while the reactivity of UEA-I was lost at the site of the completion of IRS keratinization where SBA reaction was detected. Staining of both UEA-I and SBA was prominent in other ORS cells at the levels where SBA binding in IM cells became strong. The staining intensity increased up to the position of the follicular isthmus. In addition, a sugar residue recognized by Dolichos biflorus (DBA) was detected in differentiated cells of ORS. In contrast, the DBA reaction was not found at all in cells of IRS, infundibulum, and epidermis. These findings identified a complexity of carbohydrate metabolism in the cells of different layers at various stages of keratinization. IM cells differentiate independently from other ORS cells but seem responsive to the degree of IRS keratinization. All ORS cells possess a unique sugar moiety not found in other keratinocytes either in the hair or epidermis.

Changes in lectin-binding pattern in the digestive tract of Xenopus laevis during metamorphosis. I. Gastric region

The distribution of structural and secretory glycoconjugates in the gastric region of metamorphosing Xenopus laevis was studied by the avidin-biotin-peroxidase (ABC) histochemical staining method using seven lectins (concanavalin A, Con A; Dolichos biflorus agglutinin, DBA; peanut agglutinin, PNA; Ricinus communis agglutinin I, RCA-I; soybean agglutinin, SBA; Ulex europeus agglutinin I, UEA-I; and wheat germ agglutinin, WGA). Throughout the larval period to stage 60, the epithelium consisting of surface cells and gland cells was stained in various patterns with all lectins examined, whereas the thin layer of connective tissue was positive only for RCA-I. At the beginning of metamorphic climax, the connective tissue became stained with Con A, SBA, and WGA, and its staining pattern varied with different lectins. The region just beneath the surface cells was strongly stained only with RCA-I. With the progression of development, both the epithelium and the connective tissue gradually changed their staining patterns. The surface cells, the gland cells, and the connective tissue conspicuously changed their staining patterns, respectively, for Con A and WGA; for Con A, PNA, RCA-I, SBA, and WGA; and for Con A, RCA-I, and WGA. At the completion of metamorphosis (stage 66), mucous neck cells became clearly identifiable in the epithelium, and their cytoplasm was strongly stained with DBA, PNA, RCA-I, and SBA. These results indicate that lectin histochemistry can provide good criteria for distinguishing among three epithelial cell types, namely, surface cells, gland cells, and mucous neck cells, and between adult and larval cells of each type.

Lectin cytochemistry reveals differences between hamster trachea and bronchus in the composition of epithelial surface glycoconjugates and in the response of secretory cells to neutrophil elastase

Hamsters exposed to an intratracheal instillation of human neutrophil elastase (HNE) accumulate an abnormally high number of secretory granules in bronchial but not tracheal epithelial cells. We employed lectin cytochemistry to investigate possible differences in the epithelial cell surface glycoconjugate layer in trachea compared to bronchus which might explain the regional dissimilarity in response to HNE. Portions of glutaraldehyde-fixed trachea and bronchi were incubated in one of several ferritin-labeled lectins prior to embedding for transmission electron microscopy. Lectins from Ricinus communis, Helix pomatia, and Triticum vulgaris bound to the surface of tracheal secretory cells in moderate to profuse amounts, while most bronchial secretory cells showed little or no label with these lectins. Gold-labeled Helix pomatia agglutinin (HPA), a lectin specific for secretory cells, showed a decrease in surface binding to all tracheal secretory cell types within 2 h of HNE instillation, compared to saline controls. In contrast, the majority of bronchial secretory cells showed an HNE-induced increase in surface label from extremely low levels in saline controls. The low levels of lectin binding to bronchial cells, in contrast to the trachea, may indicate the lack of a protective surface glycoconjugate coat, thus explaining the vulnerability of these cells to HNE. The rise in number of accessible HPA binding sites on the surface of bronchial secretory cells exposed to HNE may represent an important event in the pathologic accumulation of secretory granules by these cells.

Ultrastructural localization of lectin-binding sites in normal skin

The distribution of carbohydrate residues in keratinocytes of normal epidermis was studied. Normal skin was embedded in Lowicryl. Thin sections were incubated with concanavalin A (Con A), peanut agglutinin (PNA), wheat germ agglutinin (WGA), Ulex europaeus agglutinin I (UEA I), dolichos biflorus agglutinin (DBA), and soybean agglutinin (SBA). A positive reaction in the dermis, in the basal lamina (lamina densa, lamina lucida), intracellularly and within the plasma membrane including the desmosomes was obtained after incubation with Con A and WGA. PNA binding sites were found predominantly in the plasma membrane between the desmosomes. The labeling with Con A, WGA, and PNA was most pronounced in the upper stratum spinosum and granulosum. Incubation with UEA revealed heavy labeling of the keratohyalin granules and the cytoplasm of the corneocytes. Incubation with DBA and SBA revealed weak labeling of the keratinocytes. The study of the distribution of carbohydrate residues in normal epidermis is important, since alterations in this distribution might be linked to autoimmunity or malignant transformation.

Dynamic changes of cell-surface glycoconjugates in human palmar epidermis following friction-blisters

Damage and repair of cell-surface glycoconjugates were examined in human palmar skin following friction-blister injury, using biotinylated lectins and the avidin-biotin complex method. In normal skin, concanavalin A, Ricinus communis, and Triticum vulgaris bound to the surface of cells from the basal layer to the granular layer. After injury, binding of concanavalin A was absent in the plasma membrane, but appeared in the cytoplasm at perinuclear sites. The surface reaction was recovered in basal and spinous cells, but not in granular cells, when cell maturation began at 5 days after injury. In contrast, binding of Ricinus communis and Triticum vulgaris was, in general, much more resistant to tissue damage. Even in some cells, where the surface staining became obscure at an early period, a normal staining pattern reappeared by 6 h after injury. Staining of Ulex europeus I and Glycine max, detected on the surface of upper spinous and granular cells in normal skin, disappeared immediately after the injury, but recovered quickly on the surfaces of the differentiated cells. These findings suggest that at least 2 oligosaccharide sequences, one binding with concanavalin A, and the other with Ricinus communis and Triticum vulgaris, may exist on epidermal cells. Addition of terminal carbohydrates, detectable with binding of Ulex europeus I and Glycine max, appears to occur on the Ricinus communis I and Triticum vulgaris-bound oligosaccharide chain.

Differential lectin-bindings in normal and precancerous epithelium and squamous cell carcinoma of the oral mucosa

In order to establish a useful and objective marker of malignancy of oral mucosa, the binding sites for Ulex europaeus agglutinin I (UEA-I). Bandeiraea simplicifolia agglutinin I (BSA-I) and peanut agglutinin (PNA) were comparatively examined in the surgical materials from the normal, dysplastic and cancerous epithelium of the oral mucosa by a novel lectin-antilectin immunoperoxidase method. Based on the staining patterns of the normal keratinized epithelium, UEA-I was regarded as the marker for the prickle cells, BSA-I for the cells in the upper prickle to the horny layers, and PNA for those in the basal layer. As the degree of dysplasia advanced, all layers of epithelium came to react with UEA-I and PNA, whereas the BSA-I binding was negative. Positive reactions for UEA-I and PNA were seen in most carcinoma cells other than the keratinizing foci stained by BSA-I. The results indicate that a UEA-I-positive reaction in the basal cells, a PNA-positive in the prickle cells and loss of receptor for BSA-I occur in the course of malignant transformation of oral mucosa, and that these lectins may be regarded as useful markers of oral epithelial cytoplasmic differentiation.

Pemphigus foliaceus antigen: characterization of a keratinocyte envelope associated pool and preparation of a soluble immunoreactive fragment

In both the endemic and sporadic forms of pemphigus foliaceus (PF), antiepidermal autoantibodies against desmoglein I are present. Desmoglein I is a highly insoluble 160-kD transmembrane glycoprotein of the desmosomal core. The detailed immunochemical characterization of the epitope(s) recognized by the PF autoantibodies is hampered by its large molecular weight and the insolubility of desmoglein I in nondenaturing buffers. This study was designed to identify alternative methods that could yield soluble immunoreactive PF antigen (Ag) from normal human epidermis. The presence of PF Ag in human epidermis and in its soluble or insoluble fractions was monitored by indirect immunofluorescence, immunoadsorption of PF sera, and immunoprecipitation of radiolabeled fractions. The PF Ag from trypsin-resistant, radiolabeled cell envelope preparations was cleaved by papain and immunoprecipitated by PF sera. A 50-kD peptide, isoelectric at pH 5.5-5.8, was immunoprecipitated by sera from all patients with endemic PF (n = 15) or idiopathic PF (n = 4), and by two of four pemphigus vulgaris sera, but by no control sera (n = 7). This study shows that a significant fraction of the PF Ag is insoluble, trypsin-resistant, and is associated with the cornified cell envelope fraction, but an Ag fragment can be obtained in a small molecular weight, soluble, and immunoreactive form by papain digestion. This 50-kD papain fragment is more amenable to detailed chemical and immunologic characterization than the native molecule.

Biosynthesis of proteoglycans by proliferating and differentiating normal human keratinocytes cultured in serum-free medium

Normal human keratinocytes (NHK) were cultured in serum-free medium, containing low (0.1 mM) or high (2 mM) calcium, to obtain proliferating and differentiating cultures, respectively. Proteoglycan (PG) synthesis of proliferating and differentiating NHK was investigated. Cultures were labeled with 35S-sulfate, and the PGs were extracted from medium and cell layer. The newly synthesized PGs were isolated by ion-exchange chromatography on a column of DEAE-Sephacel. The molecular properties of the PGs and the size and composition of glycosaminoglycans (GAGs) were determined. In general, the PGs are relatively small size (Mr 70,000-120,000). The PGs of proliferating cultures are larger in molecular size than the PGs of differentiating cultures, and this is due to the degradation of the GAG chains. The molecular weight of the GAG chains of proliferating NHK ranged from 4,800 to 22,000, and the range for GAGs from differentiating cultures varied from 2,800 to 9,600. By compositional analysis, these PGs proved to contain heparan sulfate, chondroitin sulfate, and dermatan sulfate as determined by nitrous acid degradation, and chondroitinase ACII and ABC digestion. No significant differences were found in the overall GAG composition of the medium secreted PGs of proliferating and differentiating cultures. In contrast, cell-associated PGs of differentiating cells had higher levels of heparan sulfate than those of proliferating cells.

Demonstration by lectin cytochemistry of rod and cone photoreceptors in the lamprey retina

Lectin cytochemical analysis was undertaken to examine the distribution of glycoconjugates associated with the short and long photoreceptor cells in the lamprey retina. Concanavalin A bound preferentially to the outer segment region of the short cells. Wheat germ agglutinin bound weakly to both long and short cells. The outer segment regions of the long cells were stained intensely with peanut agglutinin. Pretreatment with neuraminidase to remove sialic acid resulted in decreased binding of wheat germ agglutinin throughout the retina and increased binding of peanut agglutinin to the outer segment region of the short cells and the region of myoid process of the long cells. These results suggest that there is a difference in the distribution of glycoconjugate residues between the long and short cells. A rod-like character of the short cell and a cone-like character of the long are tentatively discussed. Lectin-binding patterns in other retinal regions is also examined.

Changes in lectin binding pattern of gonads of developing mice

Changes in lectin binding of developing fetal mouse testes and ovaries were examined by light and electron microscopy, with much attention paid particularly to those in carbohydrates of germ cells. Characteristic binding patterns were observed with three lectins (BPA, GS-I, and GS-II) in the germ cells and the somatic cells during the process of testicular and ovarian development. GS-I and BPA, which showed similar binding patterns, preferentially bound to the plasma membrane and small dense bodies (SDB) of germ cells in both testes and ovaries during the 12th to 14th day post coitum (p.c.). In the fetal testes on day 16 p.c., the reaction with both GS-I and BPA completely disappeared. While, in the ovaries, a weak reaction with these lectins was retained as it was in germ cells until the 16th day p.c. The reaction with GS-II was restricted to Sertoli cells in the fetal testes during the 12th to 14th day p.c., and thereafter disappeared on day 16 p.c. The distribution of GS-II binding sites was in agreement with that of the glycogen granules. No positive staining with GS-II was seen in the ovaries throughout their development. These results indicate that certain glycoconjugates containing D-galactose and N-acetyl-D-galactosamine residues are expressed on the cell surface and in the SDB of germ cells during the period of the 12th to 14th day p.c., and that striking changes in function as well as in structure may take place in both germ cells and somatic cells during the 14th to 16th day p.c. in association with testicular and ovarian development.

Cellular carbohydrate components in human, rabbit and rat lacrimal gland. Studies using fluorescein and peroxidase labelled lectins

Orbital lacrimal glands from adult male and female rabbits, rats and humans were examined for the presence of intracellular receptors of four lectins: concanavalin-A agglutinin, lutus tetragonolobus agglutinin, ricinus comunis-60 agglutinin and wheat-germ agglutinin using fluorescein-conjugated lectin and peroxidase labelling methods for fluorescence and electron microscopy, respectively. Lectins were used as specific probes to detect carbohydrate moiety of the lacrimal gland. The pattern of labelling with the lectins suggests that N-acetyl-glucosamine, N-acetyl-D-galactosamine, D-galactose, D-mannose, sialic acid and L-fucose are contained in the lacrimal gland of the three species. The significance of these findings is discussed.

A type VI collagen-related glycopolypeptide is the major concanavalin A-binding component in pig skin

The major concanavalin A-binding component in urea/deoxycholate/mercaptoethanol extracts of pig skin was a collagenous disulphide-cross-linked glycopolypeptide with an apparent molecular mass of 150 kDa and a pI of 5.5. Antiserum against the electrophoretically purified glycopolypeptide gave strong dermal staining similar to that seen with fluorescent concanavalin A. Immunocytochemical labelling showed prominent labelling of 3-4 nm dermal microfilaments, particularly those associated with dermal blood vessels and mast cells. Immunoblotting with authentic antiserum indicated that the major skin glycopolypeptide was probably identical with collagen-like glycoprotein, the tissue form of the alpha 1/alpha 2 subunits of type VI collagen. This was confirmed by immunoblotting of authentic type VI collagen from pepsin-treated pig skin. Immunoblotting, metabolic labelling with [3H]glucosamine and immune precipitation showed that an immunoreactive collagenous glycopolypeptide was synthesized and secreted by cultured pig skin fibroblasts. The results suggest that type VI collagen is the major concanavalin A-binding component in pig skin.

Glycoproteins modulate adhesion in terminally differentiated keratinocytes

The stratum corneum can be dissociated into single squames by homogenization in ether. We have reaggregated the free corneocytes into a multilayered lamellar structure resembling an intact stratum corneum. The reconstituted stratum corneum reacts with fluorescein-conjugated lectins, unlike the intact tissue. We infer that the lack of binding in the intact tissue is due to masking of saccharide sites by lipids (which are extracted by the ether). In an extension of the procedure, the ether is removed and replaced by acetone. This system permits us to modulate corneocyte reaggregation by the addition of appropriate agents. We have used this system to corroborate our hypothesis that a 40 kD cell-surface glycoprotein (an endogenous lectin specific for amino sugars), which we have isolated from the stratum corneum, is instrumental in adhesion of corneocytes by cross-linking with amino sugar sites on adjacent cells. The reaggregation is inhibited by the antibody to the 40 kD glycoprotein. It is also inhibited by either the addition of amino sugars which bind to the endogenous lectin, or the addition of exogenous lectins specific for amino sugars which bind to the ligand.

An assessment of human epidermal repair in elderly normal subjects using immunohistochemical methods

The purpose of this study was to document a timetable for selected events of epidermal repair in standard partial thickness incised wounds on the legs of normal elderly human subjects. A Simplate-II bleeding-time device was used for producing the wounds, and immunohistochemical techniques were employed for evaluation of the wounds. Antibodies to filaggrin and Ulex europeus I demonstrated little or no staining on migrating epithelium, but staining was apparent whenever epidermal closure had occurred. Bullous pemphigoid antigen was present in the basement membrane zone at all time points examined, including beneath migrating epithelium, whereas antibodies to laminin and type IV collagen were found only at the most lateral aspects of 2-, 3-, and 5-day wounds. Staining progressed centrally by day 7 and was present as a complete linear band beneath most 14-day wounds. The Simplate-II device provides a standard, easy to use, commercially available, sterile, relatively safe method of producing wounds for systematic studies in humans.

Analysis of differentiation and transformation of cells by lectins

During differentiation cells are known to change their biological behavior according to their genotype. This is thought to be accompanied by a modulation of cell surface determinants expressed on the outer cell membrane. Vice versa, cell surface molecules are suggested to mediate extracellular signals to the genome. Most of these molecules integrated in the cell membrane have been proven to be glycoconjugates. The carbohydrate moieties of these molecules can be detected by means of lectins that are characterized by their ability to react specifically with distinct terminal sugar sequences. Thus, lectins have been used as appropriate tools for studying the modulation of functionally important membrane-associated molecules during the differentiation of cells, in particular of B- and T-lymphocytes. Moreover, lectins have been proven to distinguish between differentiated cells and malignant cell clones, according to the hypothesis that transformed cells possess a glycoconjugate profile that corresponds to the stage of differentiation at which they are arrested. Since lectins, like monoclonal antibodies, make it possible to study functionally important molecules that are associated with differentiation and malignancy, they might be of value for diagnostic purposes and, moreover, for analyzing malignant transformation.

Histocytochemistry of glycoconjugates in tonsillar tissues

Glycoproteins in palatine tonsillar epithelium were examined histochemically using seven different kinds of lectins to elucidate their functional morphology. UEA-I and WGA affinities, which might be altered due to an inflammatory reaction of the stroma, were detected selectively in the epithelial cell surface. Reacting products of SBA and GS-II were observed characteristically in the spinous and granular layers. No PNA, BPA and DBA activities were found in the tonsillar epithelium. These results suggest that carbohydrates on cell membranes might be changed according to the epithelial cell differentiation and some factors from the stroma.

Distribution and changes of glycoconjugates in rat colonic mucosa during development. A histochemical study using lectins

A study was made of the modifications of glycoconjugates in rat colonic mucosa during development. Sections of the caecum, and proximal and distal portions of the colon from Sprague Dawley rats at different stages of development (embryos, fetuses, suckling, weaning and adult rats) were examined. The sections were incubated with a battery of eight fluoresceinated lectins: DBA, SBA, WGA, LFA, PNA, GS-I, UEA-I and Con A. Some sections were treated with neuraminidase, and others were submitted to sequential saponification-neuraminidase treatment prior to incubation with the lectin (WGA, PNA or LFA). The intensity of the fluorescence was evaluated and graded from absent (-) to very positive (4+). Gradual and progressive changes were seen in colonic glycoconjugates during development. These changes revealed a unique developmental pattern for each lectin, which was independent for each cellular compartment (goblet cells, luminal surface and supranuclear region). Local and regional differences, observed between the different colonic sections, were already present from early stages of development. Moreover, our study showed that for several glycoconjugates, the differentiation process in colonic mucosa began in the distal region and continued through to the proximal region, the former being the first to reach the adult pattern. In the caecum, some lectins maintained a fetal pattern throughout all the periods of development up to the adult stage.

Evidence that major 78-44-kD concanavalin A-binding glycopolypeptides in pig epidermis arise from the degradation of desmosomal glycoproteins during terminal differentiation

The major concanavalin A (Con A)-binding component in urea/deoxycholate/mercaptoethanol extracts from pig ear epidermis had an apparent Mr of 78 kD. In indirect immunofluorescence affinity-purified polyclonal antibodies against this glycopolypeptide strongly stained the surface of suprabasal cells in the epidermis of pig and human skin. Immunocytochemical labeling with gold-labeled second antibody localized this staining to externally disposed, trypsin-sensitive components of desmosomes. Western blotting showed that the 78-kD glycopolypeptide was immunologically related to several other Con A-binding components in pig epidermis. Immunoreactive components with Mr of 115 and 100 kD were membrane-bound, appeared to be susceptible to trypsin in intact epidermis, and were absent from the stratum corneum. Immunoreactive components of lower Mr (78-44 kD) were not membrane-bound, were resistant to trypsin in intact tissue, and were present predominantly in the keratinized layers of pig epidermis. The 115-44-kD glycopolypeptides were also recognized by antisera raised against desmoglein II/desmocollin glycoproteins isolated from bovine spinous layer desmosomes. In addition, these antisera reacted with 120- and 105-kD bands that were apparently not recognized by the anti-78-kD glycopolypeptide antiserum in immunoblotting. In immune precipitation the anti-78-kD glycopolypeptide and antidesmoglein II/desmocollin antisera precipitated comparable amounts of the radioiodinated 78-44-kD components. Both antisera also precipitated the 120- and 105-kD components although the anti-78-kD glycopolypeptide serum was less effective. Little reaction with the 115- and 105-kD components was observed in immune precipitation with either serum. Proteolytic peptide mapping confirmed that the various immunoreactive glycopolypeptides were biochemically as well as immunologically related. The results suggest that terminal differentiation in pig epidermis is accompanied by the orderly degradation of desmoglein II/desmocollin glycoproteins resulting in the accumulation of 78-44-kD glycopolypeptides in the stratum corneum. These glycopolypeptides may represent functionally important nonmembranous domains of cell-adhesion molecules in desmosomes.

Expression of binding sites for Dolichos biflorus agglutinin at the apical aspect of collecting duct cells in rat kidney

To identify precisely the structural and functional cell type in the collecting duct of the rat kidney expressing binding sites for Dolichos biflorus agglutinin (DBA), we stained serial paraffin sections of kidney with horseradish peroxidase-labeled DBA and with immunocytochemical methods for localizing (Na+ + K+)-ATPase and carbonic anhydrase II (CA II), enzymes found preferentially in principal and intercalated cells, respectively. Most principal cells expressing a strong basolateral staining for (Na+ + K+)-ATPase showed binding sites for DBA at their luminal surfaces. However, a minority of cells rich in CA II and showing morphologic characteristics of intercalated cells also expressed DBA binding sites at their luminal surface and apical cytoplasm. These data suggest that DBA cytochemistry can provide a useful tool for studying the functional polarity of the main cell types of the collecting duct of the rat kidney.

Effects of colchicine and cytochalasin B on distribution of concanavalin A receptors in isolated and cultured guinea pig epidermal cells

Regulation of the distribution of concanavalin A (Con A)/receptor complexes by the cytoskeletal contracture system was studied in guinea pig epidermal cells in suspension and culture using the fluorescence double staining method. After treatment with 100 micrograms/ml of Con A at 37 degrees C for 30 min lectin/receptor complexes were endocytosed by the less-differentiated cells in suspension and by the adherent cells in 1- and 3-day cultures that represent a growing cell fraction. The same treatment resulted in diffuse surface distribution of the complexes in the well-differentiated cells in suspension. Colchicine (10(-5) and 10(-6) M) inhibited internalization of the complexes with resultant diffuse distribution in 60% of the adherent cells in culture. Cytochalasin B (5 and 10 micrograms/ml) not only inhibited endocytosis but promoted formation of surface patchy clumps of the complexes in suspended, less-differentiated cells and cultured adherent cells. The distribution profile was not influenced by these drug treatments in the well-differentiated cells. SDS polyacrylamide gel electrophoresis and autoradiography of 125I-labelled epidermal membranes revealed several Con A-reactive polypeptides common to the cells at various differentiation steps. The progressive decrease in endocytosis and mobility of Con A/receptor complexes was suggested to occur with differentiation. In the germinative cells the distribution of lectin/receptor complexes seemed to be regulated by microfilaments and microtubules.

Relationship between cell differentiation and binding of fluorescein isothiocyanate (FITC)-conjugated insulin of keratinocytes in culture

Basal-type keratinocytes, isolated from newborn rat skin and separated on Percoll density gradients, proliferate in low (0.1 mM) calcium medium and, after raising the calcium level to normal (1.96 mM), stratify. Cells in the low calcium culture do not have extensive cell-cell connections, as seen with fluorescein isothiocyanate (FITC)-conjugated insulin. Fluorescein isothiocyanate-conjugated concanavalin A and Griffonia simplicifolia isolectin B4, but not peanut agglutinin (PNA), fluorescently label these cells. In 3-day-old low calcium cultures, within 2 h after raising the calcium of the medium to the normal level, intense binding of PNA to cells appears and neighboring cells are connected through bundles of filaments that are fluorescently labeled by FITC-insulin. After 2 days in normal calcium medium, the cultures exhibit relatively smooth, straightlined, cell boundaries that are labeled by FITC-insulin and cell boundaries and intracellular granules that are stained by hematoxylin. One day later, similar cell boundaries are present, but they are not significantly decorated by FITC-insulin and, under phase contrast microscopy, are dark. Free FITC gives labeling patterns similar to those given by FITC-insulin, but the FITC labeling is blocked by mercaptoethanol and dithiothreitol in contrast to FITC-insulin binding. The present results suggest the insulin moiety is involved in the labeling by FITC-insulin and the labeling is chronologically related to the stage of cell differentiation.

Changes in lectin binding by differentiating cutaneous keratinocytes from the newborn rat

Surface glycoconjugates of cells from the basal layer of the skin of the newborn rat bind the isolectin I-B4 from Griffonia simplicifolia (GS I-B4) (alpha-D-galactosyl specificity). Surface glycoconjugates of the differentiated cells from the spinous and lower granular layers bind Ulex europeus agglutinin I (UEA) (alpha-L-fucosyl specificity). The change from GS I-B4 binding to UEA binding was studied in rat keratinocytes that were cultured as a monolayer in low-calcium medium until confluence, and then induced to stratify and terminally differentiate by raising the calcium concentration of the medium. The cells in the monolayer had basal cell morphology and exhibited surface binding of GS I-B4. However, at confluence, 30-40% of these cells also showed surface binding of UEA. There was an increase with time in the number of cells which bound both GS I-B4 and UEA. Raising the calcium concentration of the medium resulted in an increase in UEA binding. Cells of the upper layers of the stratifying cultures showed intense UEA binding but did not show any GS I-B4 binding. Double staining of frozen sections of newborn rat skin with fluorescein-conjugated GS I-B4 and rhodamine-conjugated UEA revealed that the surfaces of cells from the lower spinous layer bound both lectins. Thirty percent of the major glycoprotein fraction, that was isolated from the membranes of the epidermal cells of the newborn rat and was bound to an affinity column of UEA-Sepharose 4B, was also bound to an affinity column of GS I-B4-Sepharose 4B. These results indicate that surface glycoconjugates of rat keratinocytes differentiating in culture exhibit a change from GS I-B4 binding to UEA binding; the change in the cell surface glycoconjugates that results in the appearance of UEA binding, a feature of differentiated cells, occurs independently of stratification; and the change from GS I-B4 binding to UEA binding probably involves an "intermediate" glycoconjugate that binds both GS I-B4 and UEA and is found on the surface of cells from the lower spinous layer of the epidermis of the newborn rat.