Defined in situ enumeration of T6 and HLA-DR expressing epidermal Langerhans cells: morphologic and methodologic aspects

In vivo confocal microscopy of inflammatory cells in the corneal subbasal nerve plexus in patients with different subtypes of anterior uveitis

PURPOSE

Previously we could show increased numbers and densities of dendritic-like cells (DLCs) in the subbasal nerve plexus of the central cornea in patients with herpetic anterior uveitis (HAU). Now we aimed to explore these and other inflammatory cells seen in this layer in different subtypes of anterior uveitis using in vivo confocal microscopy.

METHODS

Consecutive eyes of patients with different types of anterior uveitis, HAU, Fuchs' uveitis syndrome (FUS), juvenile idiopathic arthritis (JIA) and human leucocyte antigen (HLA)-B27-related anterior uveitis were examined in vivo with the combination of Heidelberg Retina Tomograph II/III and Rostock Cornea Module. The contralateral eye was used as control. Inflammatory cells were defined on the basis of their morphology: type 1 (DLCs) and type 2 (cell bodies lacking dendrites). Frequencies were evaluated statistically in each group.

RESULTS

The difference between means of type 1 cells density of affected eyes in all four groups was significant (one-way analysis of variance (ANOVA) p=0.039). The difference between means of type 1 cell densities of affected eyes in patients with HAU (96.8±44.2 cells/mm², n=10) and that of patients with FUS (46.4±38.7 cells/mm², n=17) was significant (Tukey's post hoc p=0.025), whereas the difference between patients with HAU and JIA (53.3±34.5 cells/mm², n=7) and patients with HAU and HLA-B27 (63.1±59.2 cells/mm², n=10) was not significant (Tukey's post hoc p=0.181 and 0.300). In contrast, the following means resulted from the evaluation of type 2 cells: the difference between means of affected eyes in all four groups was not significant (one-way ANOVA p=0.185). Density means difference of patients with HAU (44.9±22.6 cells/mm², n=5) and that of FUS (20.0±11.0 cells/mm², n=2) and that of patients with JIA (56.0±18.3 cells/mm², n=2) and that of HLA-B27 (36.1±24.1 cells/mm², n=5) was not significant (Tukey's post hoc p=0.302, 0.877 and 0.739). The contralateral eye of all patient groups showed also an inflammatory cell infiltrate of lesser extent.

CONCLUSIONS

The high density and morphology of DLCs in the central cornea of patients with HAU assessed by confocal microscopy supports the clinical diagnosis of HAU especially when compared with patients with FUS but not when compared with patients with JIA or HLA-B27.

CLINICAL RELEVANCE

This study suggests that the non-invasive confocal microscopy of the cornea is capable of supporting a clinical diagnosis in patients with uveitis.

Increased Langerhan cell density and corneal nerve damage in diabetic patients: role of immune mechanisms in human diabetic neuropathy

AIM/HYPOTHESIS

Immune mechanisms have been proposed to play a role in the development of diabetic neuropathy. We employed in vivo corneal confocal microscopy (CCM) to quantify the presence and density of Langerhans cells (LCs) in relation to the extent of corneal nerve damage in Bowman's layer of the cornea in diabetic patients.

METHODS

128 diabetic patients aged 58 ± 1 yrs with a differing severity of neuropathy based on Neuropathy Deficit Score (NDS-4.7 ± 0.28) and 26 control subjects aged 53 ± 3 yrs were examined. Subjects underwent a full neurological evaluation, evaluation of corneal sensation with non-contact corneal aesthesiometry (NCCA) and corneal nerve morphology using corneal confocal microscopy (CCM).

RESULTS

The proportion of individuals with LCs was significantly increased in diabetic patients (73.8%) compared to control subjects (46.1%), P = 0.001. Furthermore, LC density (no/mm(2)) was significantly increased in diabetic patients (17.73 ± 1.45) compared to control subjects (6.94 ± 1.58), P = 0.001 and there was a significant correlation with age (r = 0.162, P = 0.047) and severity of neuropathy (r = -0.202, P = 0.02). There was a progressive decrease in corneal sensation with increasing severity of neuropathy assessed using NDS in the diabetic patients (r = 0.414, P = 0.000). Corneal nerve fibre density (P < 0.001), branch density (P < 0.001) and length (P < 0.001) were significantly decreased whilst tortuosity (P < 0.01) was increased in diabetic patients with increasing severity of diabetic neuropathy.

CONCLUSION

Utilising in vivo corneal confocal microscopy we have demonstrated increased LCs in diabetic patients particularly in the earlier phases of corneal nerve damage suggestive of an immune mediated contribution to corneal nerve damage in diabetes.

Langerhans cells and more: langerin-expressing dendritic cell subsets in the skin

Langerhans cells (LCs) are antigen-presenting dendritic cells (DCs) that reside in epithelia. The best studied example is the LC of the epidermis. By electron microscopy, their identifying feature is the unique rod- or tennis racket-shaped Birbeck granule. The phenotypic hallmark is their expression of the C-type lectin receptor langerin/CD207. Langerin, however, is also expressed on a recently discovered population of DC in the dermis and other tissues of the body. These 'dermal langerin(+) dendritic cells' are unrelated to LCs. The complex field of langerin-negative dermal DCs is not dealt with here. In this article, we briefly review the history, ontogeny, and homeostasis of LCs. More emphasis is laid on the discussion of functional properties in vivo. Novel models using genetically engineered mice are contributing tremendously to our understanding of the role of LCs in eliciting adaptive immune responses against pathogens or tumors and in inducing and maintaining tolerance against self antigens and innocuous substances in vivo. Also, innate effector functions are increasingly being recognized. Current activities in this area are reviewed, and possibilities for future exploitation of LC in medicine, e.g. for the improvement of vaccines, are contemplated.

In vivo confocal microscopic evaluation of langerhans cell density and distribution in the corneal epithelium of healthy volunteers and contact lens wearers

PURPOSE

To examine and compare the density and distribution of Langerhans cells (LCs) in the corneal epithelium of healthy volunteers and contact lens wearers.

METHODS

A total of 225 eyes of 130 healthy volunteers (age, 17-81 years) without history of ocular inflammation, trauma, or surgery and 98 eyes of 55 contact lens wearers (age, 13-76 years) were examined in vivo with the combination of the Heidelberg Retina Tomograph II and in-house-invented Rostock Cornea Module.

RESULTS

In healthy volunteers, in vivo confocal microscopy revealed LCs in 31% of all volunteers, with 37 of these 43 volunteers presenting LCs both in the center and the periphery of the cornea with densities of 34 +/- 3 and 98 +/- 8 cells/mm, respectively. In the group of contact lens wearers, 55% of all corneas presented with LCs, and 11 of these 33 corneas revealed LCs at central and peripheral locations. Although LC densities were markedly higher in both the central (78 +/- 25 cells/mm) and the peripheral cornea (210 +/- 24 cells/mm) of contact lens wearers, the gradient of LC density from peripheral to central cornea was found almost identical in both groups. In the central cornea, LC density decreased with duration of contact lens wear. LCs were located at the depth of 35 to 60 microm (ie, the level of lower intermediate cells, basal cells, and subepithelial nervous plexus). LCs presented as either large cells bearing long processes or smaller cells lacking cell dendrites, most supposedly indicating mature and immature phenotype, respectively.

CONCLUSIONS

In vivo confocal microscopy enables evaluation of LC density and distribution in corneal epithelium. LCs were found present both in the center and the periphery of the cornea without difference in distribution between healthy volunteers and contact lens wearers. However, contact lens wearers revealed almost twofold higher LC densities in both locations, implying chronic mechanical irritation of the cornea in response to the contact lens as foreign body. Taken together, analysis of LC using in vivo confocal microscopy provides helpful information for a better understanding of contact lens-disturbed ocular homeostasis.

In vivo confocal microscopic evaluation of Langerhans cell density and distribution in the normal human corneal epithelium

PURPOSE

To examine the density and distribution of Langerhans cells (LCs) in the corneal epithelium of healthy volunteers.

METHODS

Two hundred eyes of 112 healthy volunteers (age 21-81 years) without history of ocular inflammation or surgery were examined in vivo with the combination of the Heidelberg Retina Tomograph II and the Rostock Cornea Module. For statistical analysis data of one eye per volunteer were used, with random selection of one eye in those volunteers in whom both eyes were studied.

RESULTS

As studied by in vivo confocal microscopy, 31.3% of all volunteers presented with LCs (24 volunteers with both eyes studied and 11 volunteers with only one eye studied). In 30 of these 35 volunteers, LCs were found in both the central and peripheral corneal epithelium. More than 50% of male volunteers with LCs were younger than 30 years; in contrast, almost two thirds of females with LCs were above 50 years in age. The density of LCs in the periphery of the cornea (98+/-8 cells/mm2; range 0-208 cells/mm2) was significantly (p<0.001) greater than in the central part (34+/-3 cells/mm2; range 0-64 cells/mm2). LCs were located at depths of 35-60 microm, with different frequency. While LCs were sparse at the level of deep intermedial cells (5.7% of the volunteers), 11.4% of the volunteers presented with LCs within the level of basal epithelial cells and most of the eyes (82.9%) had LCs at the level of basal epithelial cells and subbasal nerve plexus. Moreover, LCs presented as either large cells bearing long processes or smaller cells lacking cell dendrites, presumably indicating mature and immature phenotype, respectively.

CONCLUSION

The Heidelberg Retina Tomograph II in combination with the Rostock Cornea Module enables in vivo assessment of density and distribution of LCs in the corneal epithelium, providing insight into human eye immunology. These data may now provide a suitable basis for further investigations in ocular pathology.

Distribution of MHC II (+) cells in skin of the Atlantic bottlenose dolphin (Tursiops truncatus): an initial investigation of dolphin dendritic cells

The skin is an important tissue of the immune system; however, little is known about immune cells in dolphin skin, and very few cetacean-specific immunoreagents are available for investigative purposes. Therefore, in this study immunohistochemistry techniques were used with species-specific and non-species-specific antibodies to characterize immune cells, primarily focusing on Langerhans cells, in skin from the Atlantic bottlenose dolphin (Tursiops truncatus). An antibody to human major histocompatibility complex (MHC) class II molecules labeled cells with a dendritic-like morphology. The immunophenotype, morphology, and distribution of some of these cells are consistent with those of Langerhans cells. The cells were predominantly found in dermal papillae, primarily along the epidermal-dermal junction. Thus, the location of these cells was somewhat different from that in terrestrial mammals. Other MHC II (+) cells of varying morphology were observed deeper in the dermis, with a perivascular concentration, and had characteristics of macrophages and dermal dendritic cells. There was no immunostaining with cetacean-specific CD2 or CD21. In diseased skin, a subjective increase of MHC II (+) cells, most notably in the superficial skin layers, was associated with an ulcerative dermatitis. A few CD2 (+) cells were also present. Differences between dolphins and terrestrial mammals in terms of morphology, mechanisms of response to insult and repair, and environmental challenges may explain the modified distribution of MHC II (+) cells in dolphin skin. An elucidation of the immune cells in cetacean skin will contribute to our understanding of the evolution of functional adaptations to various environments, facilitate diagnosis of skin diseases, and define the potential for intradermal administration of vaccines and other immunotherapeutics.

The effect of stopping smoking on cervical Langerhans' cells and lymphocytes

OBJECTIVE

To investigate the effects of stopping smoking on cervical Langerhans' cells and lymphocytes.

DESIGN

Prospective intervention study.

SETTING

A large family planning clinic in central London.

POPULATION

Women volunteers prepared to attempt to give up smoking for six months. Their most recent cervical smear showed no abnormality greater than mild dyskaryosis.

METHODS

The women were seen at three-month intervals for six months. Reduction in smoking was assessed by self-reporting and validated by salivary cotinine concentrations. Colposcopy and a biopsy of a normal area were performed at the first and last visits. Any area of abnormality was also biopsied at the final visit. Langerhans' cells and lymphocytes were counted.

MAIN OUTCOME MEASURES

Proportional changes in counts of Langerhans' cells and lymphocytes with reduction in smoking.

RESULTS

Reduction in smoking by 20 to 40 cigarettes per day was significantly associated with a reduction of between 6% and 16% in counts of Langerhans cells, CD8 and total lymphocytes. Heavy smoking was significantly associated (P = 0.02) with an increased chance of persistent human papillomavirus infection. The presence of candida was associated with significantly higher counts of between 41% and 47% in total lymphocytes and CD8 lymphocytes. In contrast, the presence of anaerobic vaginosis was associated with significantly lower counts of between 16% and 30% in Langerhans cells, CD4 and CD8 lymphocytes.

CONCLUSIONS

This large intervention study has demonstrated a clear relationship between reduction in smoking and changes in cervical immune cell counts. Future studies need to take into account cytokine interactions, which recent studies suggest may be significant in the immune response to both human papillomavirus and cervical intraepithelial neoplasia and the ever-increasing complexity of the cell-mediated immune system of the cervix.

A strikingly constant ratio exists between Langerhans cells and other epidermal cells in human skin. A stereologic study using the optical disector method and the confocal laser scanning microscope

Langerhans cells play an important part in the immune surveillance of the human epidermis. Therefore, a certain distribution and numerical relationship to other epidermal cells can be expected. To quantify epidermal Langerhans cells population extensive studies have been performed using two-dimensional quantification methods on vertical sections or epidermal sheet preparations. Whereas methods using vertical sections were complicated considerably by the sampling procedure, the dendritic shape, and the suprabasal, nonrandom distribution of Langerhans cells, epidermal sheet preparations have their limitations regarding the numerical relationship of Langerhans cells to total epidermal cells and the epidermal morphology as such. In order to improve the validity of data the three-dimensional dissector method combined with confocal laser scanning microscopy has been applied to quantify the number of Langerhans cells and other epidermal cell nuclei per volume unit in cryosections of 24 punch biopsies of normal breast skin of eight women. Furthermore, the ratio of Langerhans cells to other epidermal cells, their number per biopsy, and per skin surface area were calculated. To minimize the bias by shrinkage the reference volume was estimated using Cavalieri's principle. A constant ratio of one Langerhans cells to 53 other epidermal cells was identified in breast skin (interindividual correlation coefficient: 0.952, p < 0.0001). Thus, Langerhans cells represent 1.86% of all epidermal cells; however, a wide interindividual range was found for the number of Langerhans cells per mm2 (912-1806; mean +/- SD 1394 +/- 321) and other epidermal cells per mm2 (47,315-104,588; mean +/- SD 73,952 +/- 19,426). This explains the conflicting results achieved by conventional morphometric assessments relating cell numbers to skin surface area, ignoring the varying thickness of the epidermis. The surprisingly constant relationship of Langerhans cells to other epidermal cells stresses the hypothesis of an epidermal Langerhans cells unit where one Langerhans cells seems to be responsible for the immune surveillance of 53 epidermal cells.

An automated method for the quantification of immunostained human Langerhans cells

Allergic contact dermatitis is a frequent and increasing health problem. For ethical reasons, the current animal tests used to screen for contact sensitizers should be replaced by in vitro alternatives. Contact sensitizers have been shown to accelerate Langerhans cell (LC) migration from human organotypic skin explant cultures (hOSECs) more rapidly than non-sensitizers and it has been proposed that the hOSEC model could be used to screen for sensitizers. However, chemically induced decreases in epidermal LC numbers need to be accurately quantified if the alterations in epidermal LC numbers are to form the basis of an alternative system for screening contact sensitizers in vitro. As manual counting of LCs is labour intensive and subject to intra- and inter-personal variation we developed an image analysis routine, using the Leica QWin image analysis software, to quantify LCs in situ using immunohistochemically stained skin sections. LCs can be identified using antibodies against the membrane molecule CD1a or the Lag antibody, which recognises cytoplasmic Birbeck granules. Quantification of epidermal LC number using the image analysis software had a much lower inter-person variation than when the same specimens were counted manually, using both the anti-Lag and CD1a antibodies. The software-aided quantification of epidermal LCs provides an accurate method for measuring chemically-induced changes in LC numbers.

Downregulation of class II molecules on epidermal Langerhans cells in Lyme borreliosis

BACKGROUND

Borrelia burgdorferi can be isolated from the skin of patients with acrodermatitis chronica atrophicans (ACA), a late-stage manifestation of Lyme borreliosis; despite a marked T-cell infiltrate in lesional skin and high antibody titres in patients' sera.

OBJECTIVES

To determine whether antigen-presenting Langerhans cells (LCs), which reportedly show signs of injury in erythema chronicum migrans (ECM), the early stage of disease, are altered in ACA.

PATIENTS/METHODS

We studied the immunophenotype of cutaneous leucocytes on cryostat sections of lesional skin from both ECM and ACA patients.

RESULTS

The total number of CD1a+ cells evaluated by semiautomatic image analysis was lower in ECM (594 +/- 263 cells mm(-2) epidermis) than in ACA (835 +/- 317 cells mm(-2) epidermis). HLA-DR expression was remarkably downregulated on CD1a+ LCs to 29% in ECM and 18% in ACA, whereas in normal skin, most of the epidermal CD1a+ dendritic cells were HLA-DR+. The inflammatory infiltrate was mainly composed of CD68+ macrophages and CD45RO+ memory T cells, with a predominance of CD4+ helper T cells.

CONCLUSIONS

It is conceivable that the downregulation of major histocompatibility complex class II molecules on LC in both the early and late skin manifestations of Lyme borreliosis is indicative of a poorly effective anti-B. burgdorferi immune response and thus at least partly responsible for the insufficient elimination of this micro-organism from ACA skin.

The antigen-presenting environment in normal and human papillomavirus (HPV)-related premalignant cervical epithelium

The activation of HPV-specific T cells within the cervical microenvironment is likely to play an important part in the natural history of cervical intraepithelial neoplasia (CIN). The extent and the type of T cell activation will depend critically on the expression of MHC, costimulatory cell surface molecules and cytokines by keratinocytes and Langerhans cells within the cervical lesion. Expression of MHC class II (HLA-A-DR and -DQ), costimulatory/adhesion molecules (CD11a/18, CD50, CD54, CD58 and CD86) and cytokines (tumour necrosis factor-alpha (TNF-alpha) and IL-10) was therefore investigated by immunohistochemistry in normal squamous epithelium (n = 12), low-grade (n = 23) and high-grade (n = 18) squamous intraepithelial lesions of the cervix. CIN progression was associated with de novo expression of HLA-DR and CD54, and increased expression of CD58 by keratinocytes. However, significantly, there was no expression of any adhesion/costimulation molecule by epithelial Langerhans cells in any cervical biopsy studied. Furthermore, TNF-alpha, a potent activator of Langerhans cells, was expressed constitutively by basal keratinocytes in normal cervix (12+/12). but expression of this cytokine was absent in a number of CIN samples (20+/23 for low-grade, 12+/18 for high-grade CIN). Conversely, the suppressive cytokine IL-10 was absent in normal epithelium (0+/12), but was up-regulated in a number of CIN lesions (12+/23 for low-grade; 8+/18 for high-grade CIN). The restricted expression of costimulation/adhesion molecules and the nature of the cytokine microenvironment within the epithelium may act to limit effective immune responses in some CIN lesions.

Lymphocytes and dendritic cells in the normal uterine cervix. An immunohistochemical study

OBJECTIVE

Assessment of the appearance, distribution and numerical density of immune cell populations in the normal human uterine cervix.

STUDY DESIGN

SETTING

University Hospital Gasthuisberg.

SUBJECTS

29 healthy women undergoing total hysterectomy for non-cervical benign uterine disease.

ANALYSIS

Immunohistochemistry and morphometrical analysis on histological sections containing ectocervix, transformation zone and endocervix, using antibodies against the following antigens: HLA-DR, CD4, CD22, CD1a and CD8.

STATISTICAL ANALYSIS

Wilcoxon rank sum test.

RESULTS

Lymphocytes in the epithelial and stromal compartments are predominantly T-lymphocytes. Intraepithelial T-lymphocyte and Langerhans' cell densities and their distribution are not influenced by the menstrual cycle and are the same in both ectocervix and transformation zone.

CONCLUSION

The wide variation of T lymphocyte subpopulations and Langerhans' cell densities in the normal epithelium of the uterine cervix is stressed. We are the first to present a large and well-defined control series, which is indispensable to study the effect of smoking and other factors on the cervical immune system.

Differential regulation of HLA-DQ expression by keratinocytes and Langerhans cells in normal and premalignant cervical epithelium

Keratinocytes in normal ectocervix did not express major histocompatibility complex class II molecules. In low-grade intraepithelial lesions expression was confined to HLA-DR, while in high-grade disease there was expression of HLA-DR and occasional expression of HLA-DQ. HLA-DR was expressed constitutively on the majority of Langerhans cells. In contrast, few Langerhans cells expressed HLA-DQ in normal cervix, but there was a steady upregulation of the proportion expressing HLA-DQ which paralleled the severity of disease. There was no direct correlation between human papillomavirus 16 and the expression of major histocompatibility complex class II by keratinocytes and Langerhans cells. Significant upregulation of HLA-DQ by Langerhans cells is observed in high-grade intraepithelial cervical lesions, suggesting antigen-presenting cell activation in papillomavirus-related premalignant disease.

Oral mucosal Langerhans' cells

Langerhans' cells (LC) are dendritic, antigen-presenting cells present within the epithelium of skin and mucosa, including that of the oral cavity. This article reviews the literature on the phenotypic and functional features of oral mucosal Langerhans' cells, and speculates on other aspects by extrapolating from data on their epidermal counterparts.

Effect of topical tretinoin on epidermal Langerhans' cells in photodamaged skin

BACKGROUND

Topical tretinoin has been successfully applied to treat photoaging; however, a decrease in the number of Langerhans' cells (LC) has been reported after its topical application in Macaque skin. A study was performed to evaluate the possible effect of topical tretinoin on the number of LC in human beings.

METHODS

Eight patients were studied. Topical tretinoin was applied in progressively increasing concentrations: 0.025% for 1 month, 0.05% for one month and 0.1% for 4 months. A skin biopsy from the malar area was taken before this therapy and 6 months later. To study LC, 4 mu frozen sectionswere stained with the anti-CD1 antibody.

RESULTS

The number of CD1+ cells did not change when they were counted per unit of epidermal length, but they decreased when they were counted per unit of epidermal surface.

CONCLUSIONS

These results indicate that topical tretinoin might damage epidermal Langerhans' cells, when it is applied for long periods of time; future studies are necessary to clarify this point.

HLA-DR expression is induced on keratinocytes in delayed hypersensitivity but not in allergen induced late-phase reactions

In view of increasing evidence suggesting an active immunoregulatory role of the skin keratinocytes and the observation that the differentiation of allergen specific T lymphocytes is critical in the development of allergy, we evaluated epidermal expression of HLA-DR antigen in skin reactions induced with an atopen (house dust mite) and with an non-atopic antigen (Hemocyanin). Two groups of patients with house dust mite (Dermatophagoides pteronyssinus [Der p]) allergy were compared, one group was skin tested with Der p, the other group was immunized and subsequently skin tested with Helix pomatia Hemocyanin (HPH). Biopsy specimens taken at 48 h after the HPH (n = 11) and Der p (n = 11) tests were analysed immunohistologically. Reactions in both groups were comparable in size. Immunohistological analysis showed domination by CD4+ lymphocytes. Expression of HLA-DR antigen by epidermal keratinocytes was observed in six out of 11 of the HPH induced reactions, but in none of the Der p induced reactions. Eosinophils were spotted only throughout the Der p induced reactions, showing a good correlation with the number of CD4 positive lymphocytes. The lack of HLA-DR expression by keratinocytes during the allergen-induced reaction, compared with the Hemocyanin induced reaction can be the result of a difference in cytokine profile of the lymphocytes dominating the dermal infiltrate. On the other hand evidence exists that defective HLA-DR expression by keratinocytes enhances antigen induced lymphocyte activation, and may thus contribute to the development of allergen-specific T-lymphocytes.

Effect of tobacco and alcohol consumption on the Langerhans cell population of human lingual epithelium determined using a monoclonal antibody against HLADR

Tobacco and alcohol consumption are known predisposing factors to the development of oral cancer, though the mechanism by which they act is unclear. The density of Langerhans cells (LC) has been shown to decrease in the uterine cervix of smokers, possibly indicating reduced immune surveillance and increased risk of malignant change. This study examined biopsies of normal human lateral border of tongue taken from 41 necropsies whose histories of tobacco and alcohol consumption were known. LC were identified in fixed, wax-embedded sections using a monoclonal antibody to HLADR and an immunoperoxidase technique. The mean density of LC in smokers of the equivalent of 11 or more cigarettes daily was significantly higher than moderate and non-smokers when counts were expressed per mm epithelial surface and basement membrane length. There were no significant differences in LC numbers in relation to alcohol consumption, age or sex, but there was a significant interaction between tobacco and alcohol. The results suggest that either human oral LC respond to external toxins, or that physical changes in the epithelial barrier induced by such toxins necessitate the presence of more LC to maintain the integrity of the epithelium.

Differential effects of structurally unrelated chemical irritants on the density and morphology of epidermal CD1+ cells

In order to gain a greater insight into the complex mechanisms of action of different irritant chemicals on the skin, we have studied the behavior of epidermal CD1+ cells in experimentally induced irritant contact dermatitis. Healthy, human volunteers were patch tested for 48 h with the following six chemically unrelated irritants and their appropriate vehicle controls; benzalkonium chloride, sodium lauryl sulphate, dithranol, nonanoic acid, croton oil, and propylene glycol. After visually assessing and grading the resulting inflammatory reactions, punch biopsies were taken and the morphology and density of CD1+ cells in the epidermis studied using immunocytochemical techniques in combination with image analysis and electron microscopy. Statistically significant decreases in the epidermal density of CD1+ cells occurred in the responses to dithranol (p less than 0.05) and nonanoic acid (p less than 0.01). Importantly, these changes in density were not simply due to variations in the intensity of inflammatory response (r = 0.1157). Alterations in the length of the dendritic processes of CD1+ cells were also induced, and semi-quantitative analysis revealed significant decreases in dendrite length in the reactions to sodium lauryl sulphate (p less than 0.05), nonanoic acid (p less than 0.001), croton oil (p less than 0.05), and dithranol (p less than 0.005). Unlike epidermal density, however, this effect on cell morphology was directly related to the severity of inflammation (r = -0.74, p less than 0.01). Morphologic evidence of cellular injury to Langerhans cells was seen by electron microscopy in the majority of biopsies, although relatively few cells were affected in sodium lauryl sulphate and propylene glycol reactions. Benzalkonium chloride, unlike the other irritants, also induced a state of metabolic activation in a high proportion of epidermal Langerhans cells. Lymphocyte/Langerhans cell apposition was observed in most samples, but was particularly prevalent in the reactions to dithranol. The results of this study demonstrate that significant changes in the morphology and density of Langerhans cells occur in irritant contact dermatitis, some of which are directly influenced by the chemical nature of the irritant.

Langerhans cells in human allergic contact dermatitis contain varying numbers of Birbeck granules. Double staining immunohistochemistry with OKT6 and Lag antibody

Dynamic changes in human Langerhans cells (LCs) were studied with OKT6, anti-HLA-DR antibody, and Lag antibody in allergic contact dermatitis (ACD). Both T6-positive (T6+) cells and Lag-positive (Lag+) cells in the epidermis decreased in number from 0 to 48 h, but then gradually increased after day 7 of ACD. Lag+ cells after day 7 manifested a variety of staining intensities from weak to strong. It was also shown, after day 7, that some T6+ cells were Lag negative whereas all Lag+ cells were T6 positive. Flow cytometric analysis suggested that Lag-strongly-positive cells and Lag-weakly-positive cells belonged to the same population, and that the relative amount of Lag antigens in T6+ LCs gradually increased after day 7. Immunoelectron microscopy revealed that the Lag-strongly-positive cells contained numerous Lag-reactive Birbeck granules (BGs) whereas the Lag-weakly-positive cells contained fewer BGs in the cytoplasm. In some Lag-weakly-positive cells, no BGs were detected.

An immunohistological study of condylomata acuminata

Using an indirect immunoperoxidase method and a panel of monoclonal antibodies, anogenital warts removed from 86 individuals (28 heterosexual men, 47 homosexual men and 11 women) were studied. A constant feature was the presence of a stromal infiltrate of lymphocytes, in which CD4+ and CD8+ cells appeared in a ratio of about 5:1. Cells expressing interleukin-2 receptors were found in the stroma, amounting to 10% of the CD3+ cells. Leu 6+ epidermal dendritic cells (Langerhans' cells) were present in each wart; their density and morphology were similar to that in adjacent, apparently normal, skin. The mean number of Langerhans' cells that expressed HLA-DQ was lower than that of HLA-DR + cells. In 40 warts, HLA-DR was expressed on the surface of keratinocytes. Leu 7+ and Leu 11b+ cells were found in the epidermis of 17 and five warts, respectively. B-cells were noted in only five warts. These results are discussed in relation to persistence of wart virus infection.

Epidermal Langerhans' cell densities influence survival in mycosis fungoides and Sézary syndrome

Because Langerhans' cells (LC) (CD1a-positive epidermal cells) have been discussed to be involved in the pathogenesis of mycosis fungoides and Sézary syndrome, the authors examined the influence of densities of Langerhans' cells and, concurrently, of other phenotypes retrospectively on survival of 35 patients. Cell densities were assessed on cryostat sections (alkaline phosphatase antialkaline phosphatase-technique) of the respective diagnostic biopsy specimens. Additionally, two clinical parameters (age, stage of disease) were evaluated. CD1a-positive epidermal cells were demonstrated to be the only cell population being significantly associated (P = 0.011) with survival. Death resulting from mycosis fungoides and Sézary syndrome was significantly (P = 0.003) less frequent in patients with epidermal CD1a-positive cell densities higher than 90 cells/mm2 (optimal break point) as compared with patients with lower numbers. These results suggest that Langerhans' cells have a significant impact on prognosis of patients with mycosis fungoides and Sézary syndrome. They play an important role in the host defense mechanisms against these lymphomas rather than to favor their progression as proposed recently.

Correction of human immunodeficiency virus-associated depression of delayed-type hypersensitivity (DTH) after zidovudine therapy: DTH, CD4+ T-cell numbers, and epidermal Langerhans cell density are independent variables

Twenty-four patients with various degrees of human immunodeficiency virus (HIV)-associated immunodeficiency were treated with zidovudine for up to 6 months. Nineteen of these patients had persistent depression of delayed-type hypersensitivity (DTH) responses prior to commencing therapy. In 11 of these 19 patients (58%) there was sustained improvement of DTH responses with the maximal effect occurring at approximately 3 months after therapy was started. DTH declined after 3 months but remained significantly higher than baseline at 6 months. Patients who did not have a sustained increase in DTH responses had more severe disease than those that did. Blood CD4+ T-cell counts increased in the majority of patients on zidovudine therapy, but varied independently of DTH responses. Epidermal Langerhans cell density was lower in HIV-infected patients than controls but also varied independently of DTH responses before and after zidovudine therapy. We suggest that sequential measurement of DTH responses is a valuable means of monitoring the restoration of cell-mediated immune responses by zidovudine in some HIV-infected patients. Our findings also demonstrate the need to define the processes involved in the restoration of DTH responses as this may lead to new approaches to the therapeutic manipulation of cell-mediated immune responses in HIV-infected patients.

T lymphocytes, Langerhans cells and HLA-DR expression on keratinocytes in oral lesions associated with amalgam restorations

It has been shown recently that patients with mucosal lesions confined to areas opposing amalgam restorations (contact lesions) show a high rate of allergic reaction towards mercury. These lesions may, therefore, represent a contact hypersensitivity reaction. Contact lesions often have a lichenoid appearance. From a pathogenetic and differential diagnostic point of view we therefore evaluated the presence of lymphocyte subpopulations, Langerhans cells (LC) and the expression of HLA-DR antigens on mucosal keratinocytes in biopsies of contact lesions (Group 1) and in lichen planus lesions with (Group 2) and without (Group 3) partial contact with amalgam restorations. T lymphocytes dominated in all three groups and LC counts were similar. HLA-DR positive keratinocytes were found in 18-36% of lesions in all three groups. Thus, the immunologic parameters examined are not of value in discriminating between the types of lesions studied. Rather, it seems that the pattern observed is a common reaction of the oral mucosa to known (amalgam restorations) and unknown factors.

Lymphocytes and macrophages of the epidermis and dermis in lesional psoriatic skin, but not epidermal Langerhans cells, are depleted by treatment with cyclosporin A

Since cyclosporin A (CsA) is an immunosuppressive agent, its beneficial effect in psoriasis suggests that immune cells may play a role in the pathogenesis and resolution of psoriasis. To determine early effects of CsA in psoriasis, we quantitated immune cells using double immunofluorescence microscopy on biopsy specimens obtained prior to therapy and after 3, 7, and 14 days of CsA therapy. CsA therapy resulted in significant reductions in the absolute number of immune cells (including T cells, monocytes/macrophages, and antigen presenting cells) contained within psoriatic skin. The effect was rapid, with over one-half of the reduction in the density of HLe1+ (human leukocyte antigen-1 positive or bone marrow derived) cells, including T cells, activated T cells, monocytes, and Langerhans cells (LCs), occurring within 3 days. Despite the overall reduction in the numbers of immunocytes in the skin, the proportion of T cells, Langerhans cells, and monocytes in relation to the total number of immune cells was unchanged with therapy, reflecting equally proportional losses of each subtype. Dermal CD1+DR+ cells (putative Langerhans cells), which are not found in normal skin but are present in lesional psoriasis skin, were virtually cleared from the papillary dermis after CsA therapy. Although absolute numbers of epidermal Langerhans cells, defined as cells expressing both CD1 (T6) and DR molecules (CD1+DR+), were also reduced after CsA, epidermal non-Langerhans CD1-DR+ cells (macrophages, activated T cells, DR- keratinocytes) demonstrated a proportionally greater decrease, with the ratio of CD1+DR+ Langerhans cells/non-Langerhans CD1-DR+ epidermal cells changing from a mean of 0.82 at baseline to 1.92 at day 14.(ABSTRACT TRUNCATED AT 250 WORDS)

Flow cytometric analysis and sorting of HLA-DR+CD1+ Langerhans cells

There is a considerable need for reliable methods for enumeration and enrichment of Langerhans cells (LCs), since they continue to be the subject of intensive investigation in normal and diseased skin. It has been claimed that standard labelling with either anti-HLA-DR or OKT6 antibodies alone may fail to identify potentially important subsets of LCs with the phenotypes HLA-DR+CD1- and HLA-DR-CD1+. We report here on flow cytometric analysis of suction blister-derived normal epidermal cell (EC) suspensions, double stained with phycoerythrin-conjugated anti-HLA-DR and fluoresceinated OKT6. In seven separate experiments, no evidence for the existence of either HLA-DR+CDI- or HLA-DR-CDI+ ECs was obtained. We found that HLA-DR+CDI+LCs, which constituted a mean of 2.5% (+/- 0.3 SEM) of all ECs, could be readily identified on the basis of fluorescence, and that their light scatter characteristics were those of moderately sized cells of low granularity. We further describe our method for flow cytometric enrichment of such HLA-DR+CDi+ LCs for functional studies, based on selection on both fluorescence and light scatter criteria. Enrichment is to greater than 90% purity, and the method is applicable to the small number of ECs (approximately 1 x 10(6] obtained from a suction blister.

Occurrence of Langerhans cells and expression of class II antigens on keratinocytes in malignant and benign epithelial tumors of the skin: an immunohistopathologic study with monoclonal antibodies

We used an avidin-biotin complex immunoperoxidase technique with various monoclonal antibodies to determine Langerhans cell densities, class II antigen expression on keratinocytes, and phenotypes of other infiltrating cells in several malignant and benign epithelial tumors of the skin. Our observations indicate (1) there are few Langerhans cells in nests of basal cell carcinoma and squamous cell carcinoma; (2) there are increased Langerhans cell densities in seborrheic keratoses, verrucous epidermal nevus, and Bowen's disease; (3) there is an expression of class II molecules on the keratinocytes and cancer cells of basal cell carcinoma, squamous cell carcinoma, Bowen's disease, seborrheic keratosis, and verrucous epidermal nevus; and (4) there is a netlike staining of the keratinocyte surface with OKM5 in the epidermal lesion of seborrheic keratosis, verrucous epidermal nevus, and Bowen's disease, as well as in the epidermis adjacent to the basal cell carcinoma and squamous cell carcinoma nests.

Keratinocytes in lesional skin of atopic eczema bear HLA-DR, CD1a and IgE molecules

Apparently normal, and lesional skin from patients with atopic eczema were investigated immunohistochemically with anti-HLA-DR, -CD1a and -IgE antisera. A CD1a+ intercellular pattern was observed in uninvolved skin in the majority of the patients whereas an HLA-DR+/CD1a+ network, mostly localized in basal and supra-basal areas, was shown in lesional skin of virtually all of them. Moreover, an HLA-DR+/CD1a+IgE+ intercellular pattern was observed in some of the patients only and was predominantly localized in those areas characterized by lymphocyte exocytosis, spongiosis or vesicle formation. Whether keratinocytes are able to synthesize CD1a antigen and Fc epsilon R or if these molecules are only produced and shed by CD1a+/IgE+ epidermal dendritic cells remains unclear.

Comparison of different methods for enumeration of Langerhans cells in vertical cryosections of human skin

We have quantified Langerhans cells (LC) in cryosections of normal human skin and lesional skin from patients with atopic eczema and psoriasis vulgaris using six different methods. The results from the different methods varied considerably and were sometimes contradictory, for example when LC numbers in psoriatic skin were compared with those in normal skin. Thus, in addition to the staining technique used and the selection of the dendritic cell type to be counted, the enumeration method used can also influence the quantitation of LC in normal and pathological skin.

Expression of major histocompatibility class II antigens by Langerhans' cells in cervical intraepithelial neoplasia

Cervical biopsy samples from 67 patients who had various grades of cervical intraepithelial neoplasia (CIN) or who showed evidence, in the form of koilocytosis, of human papillomavirus (HPV) infection of the uterine cervix, and from 10 women with normal cervices were examined. Cryostat sections from the biopsy samples were stained using monoclonal antibodies to T6, a Langerhans' cell marker, and to major histocompatibility complex (MHC) class II antigens (HLA-DP, DQ, and DR). Epithelial Langerhans' cells were reduced in number and showed changed morphology and distribution in koilocytic lesions and in all grades of CIN (p less than 0.01) except CIN I. HLA-DR expression by Langerhans' cells was significantly increased in koilocytic lesions and in CIN grades I and II (p less than 0.05); HLA-DQ expression was significantly increased in all grades of CIN (p less than 0.05) with the increase being most pronounced in CIN I (p less than 0.01). Columnar epithelium expressed MHC class II antigens in all samples tested and squamous epithelium in four of 29 cases of CIN III. These findings support the view that there is a localised disturbance of immune function in both neoplastic cervical epithelium and that infected with papillomavirus.

Immunocytochemical examination of immune cells in periapical granulomata and odontogenic cysts

Monoclonal antibodies (mAbs) were used to determine the presence and distribution of immune cells including lymphocytes, macrophages and Langerhans cells, in normal periodontal ligament, periapical granulomata, periapical cysts and dental developmental cysts. Isolated T-lymphocytes, but not B-lymphocytes, were detected in specimens of non-inflamed periodontal ligament. Increased numbers of T and B lymphocytes were found in all of the lesions examined. Monocytes/macrophages were associated with most periapical granulomata, dental developmental cysts and all periapical cysts. Langerhans cells, intraepithelial lymphocytes, and monocytes/macrophages were not detected in the rests of Malassez but were found in some epithelia within periapical granulomata and in most epithelial linings of odontogenic cysts. Increased numbers of immune cells were seen around proliferative epithelia and adjacent to the epithelial linings of cysts. Epithelium, particularly that of odontogenic cysts, showed positive reactions for HLA-Dr, lysozyme and for alpha-1 antitrypsin. The presence of immune cells in periapical granulomata and odontogenic cysts, suggests that cell-mediated and humoral immunoreactions occur in these lesions and may be associated with the epithelial proliferation within the periapical lesions.

HLA-DR expression by hair follicle keratinocytes in alopecia areata: evidence that it is secondary to the lymphoid infiltration

There is evidence suggesting that alopecia areata (AA) may have an autoimmune pathogenesis, and it was recently reported that keratinocytes in the bulb of some hair follicles affected by this condition express class II HLA (HLA-DR) antigens, which are not present on the same cells in normal tissue. Since it has been proposed that an analogous ectopic HLA-DR expression by epithelial cells in other organs might be an early event leading to organ-specific autoimmunity, we have investigated the sequence in which perifollicular mononuclear cell (MNC) infiltration and ectopic HLA-DR expression on keratinocytes appear in recent-onset and long-standing cases of AA by immunostainings of affected and unaffected areas with monoclonal antibodies against leukocyte and HLA-DR antigens. In recent-onset AA lesions, ectopic HLA-DR expression on hair follicle keratinocytes was found only occasionally (in 3 out of 247 follicles examined) and was restricted to biopsies from the affected areas. This prevalence was significantly lower than the prevalence of hair follicles showing perifollicular MNC infiltrates in the same biopsies, and was also significantly lower than the prevalence of hair follicles showing ectopic HLA-DR expression on keratinocytes in the affected areas of longstanding cases. These findings suggest that in AA lesions the perifollicular MNC infiltration precedes the ectopic HLA-DR expression on hair follicle keratinocytes, and therefore argue against the notion of a primary role for that ectopic HLA-DR expression on epithelial cells in triggering the putative autoimmune response in AA.

Epidermodysplasia verruciformis: Langerhans cells, immunologic effect of retinoid treatment and cytogenetics

A case study is presented of a 44-year-old negroid male with epidermodysplasia verruciformis (EV), cutaneous carcinomas, and impaired cell-mediated immunity (CMI), infected with human papillomavirus type 8 and 17. Analysis was made of (a) T6+ and HLA-DR+ Langerhans cells (LCs) by immunoperoxidase staining in lesional and clinically normal skin before and during retinoid treatment, (b) the effect of retinoid treatment on CMI in vivo and in vitro, and (c) cytogenetic aspects related to chromosomal instability. The results showed the virtual absence of T6+ and HLA-DR+ LCs in koilocytic areas of epidermis involved with EV. Light-exposed, clinically normal skin also demonstrated microscopic EV lesions largely devoid of T6+ and HLA-DR+ LCs. Retinoid treatment with etretinate (Ro 10-9359) appeared both to increase the CMI response in vitro to T-cell mitogens and to influence the in situ pattern of T6+ and HLA-DR+ LCs. The cytogenetic study did not show evidence of spontaneous or UV-induced chromosomal instability.

Dual expression of the cell-surface antigens HLA-DR and CD1 (T6) by Langerhans cells in human buccal mucosa and skin

The expression of HLA-DR and CD1 (T6) by Langerhans cells (LC) in human buccal mucosa and skin was investigated with the monoclonal antibodies YE2/36HLK (HLA-DR) and HTA1-C1 (CD1). A five-stage sequential double immunofluorescent-labelling technique, with rhodamine and fluorescein as the fluorochromes, was used to visualize the two surface antigens in the same microscope field. The majority of LC in cryostat sections of buccal mucosa and skin expressed both HLA-DR and CD1.