Distribution of ATPase-positive Langerhans cells in normal adult human skin

Nucleic Acid-Based Approaches for Tumor Therapy

Within the last decade, the introduction of checkpoint inhibitors proposed to boost the patients' anti-tumor immune response has proven the efficacy of immunotherapeutic approaches for tumor therapy. Furthermore, especially in the context of the development of biocompatible, cell type targeting nano-carriers, nucleic acid-based drugs aimed to initiate and to enhance anti-tumor responses have come of age. This review intends to provide a comprehensive overview of the current state of the therapeutic use of nucleic acids for cancer treatment on various levels, comprising (i) mRNA and DNA-based vaccines to be expressed by antigen presenting cells evoking sustained anti-tumor T cell responses, (ii) molecular adjuvants, (iii) strategies to inhibit/reprogram tumor-induced regulatory immune cells e.g., by RNA interference (RNAi), (iv) genetically tailored T cells and natural killer cells to directly recognize tumor antigens, and (v) killing of tumor cells, and reprograming of constituents of the tumor microenvironment by gene transfer and RNAi. Aside from further improvements of individual nucleic acid-based drugs, the major perspective for successful cancer therapy will be combination treatments employing conventional regimens as well as immunotherapeutics like checkpoint inhibitors and nucleic acid-based drugs, each acting on several levels to adequately counter-act tumor immune evasion.

DNA Vaccines-How Far From Clinical Use?

Two decades ago successful transfection of antigen presenting cells (APC) in vivo was demonstrated which resulted in the induction of primary adaptive immune responses. Due to the good biocompatibility of plasmid DNA, their cost-efficient production and long shelf life, many researchers aimed to develop DNA vaccine-based immunotherapeutic strategies for treatment of infections and cancer, but also autoimmune diseases and allergies. This review aims to summarize our current knowledge on the course of action of DNA vaccines, and which factors are responsible for the poor immunogenicity in human so far. Important optimization steps that improve DNA transfection efficiency comprise the introduction of DNA-complexing nano-carriers aimed to prevent extracellular DNA degradation, enabling APC targeting, and enhanced endo/lysosomal escape of DNA. Attachment of virus-derived nuclear localization sequences facilitates nuclear entry of DNA. Improvements in DNA vaccine design include the use of APC-specific promotors for transcriptional targeting, the arrangement of multiple antigen sequences, the co-delivery of molecular adjuvants to prevent tolerance induction, and strategies to circumvent potential inhibitory effects of the vector backbone. Successful clinical use of DNA vaccines may require combined employment of all of these parameters, and combination treatment with additional drugs.

Efficacy, Safety and Targets in Topical and Transdermal Active and Excipient Delivery

A key requirement for topical and transdermal active delivery is the effective delivery of an active to a desired target site, to achieve both safe and efficacious outcomes. This chapter seeks to explore the importance of the pharmacological, toxicological and therapeutic properties of actives and excipients, as well as the site of action as complementary components in percutaneous absorption. This is crucial for optimized topical and transdermal product design.

Pronounced reduction of cutaneous Langerhans cell density in recently diagnosed type 2 diabetes

Immune-mediated processes have been implicated in the pathogenesis of diabetic polyneuropathy. Langerhans cells (LCs) are the sole dendritic cell type located in the healthy epidermis and exert tolerogenic immune functions. We aimed to determine whether alterations in cutaneous LC density and intraepidermal nerve fiber density (IENFD) are present in patients with recently diagnosed type 2 diabetes. Skin biopsy specimens from the distal leg from 96 type 2 diabetic patients and 75 healthy control subjects were used for quantification of LC density and IENFD. LCs and IENFs were labeled using immunohistochemistry. Nerve conduction studies, quantitative sensory testing, and neurological examination were used to assess peripheral nerve function. LC density was markedly reduced in the diabetic group compared with the control group, but did not correlate with reduced IENFD or peripheral nerve function. Multivariate linear regression analysis revealed a strong association between LC density and whole-body insulin sensitivity in women but not in men with diabetes. Prospective studies should establish whether the pronounced reduction of cutaneous LCs detected in recently diagnosed type 2 diabetes could promote a cutaneous immunogenic imbalance toward inflammation predisposing to polyneuropathy and foot ulcers.

Needle-free vaccine injection

Millions of people die each year from infectious disease, with a main stumbling block being our limited ability to deliver vaccines to optimal sites in the body. Specifically, effective methods to deliver vaccines into outer skin and mucosal layers--sites with immunological, physical and practical advantages that cannot be targeted via traditional delivery methods--are lacking. This chapter investigates the challenge for physical delivery approaches that are primarily needle-free. We examine the skin's structural and immunogenic properties in the context of the physical cell targeting requirements of the viable epidermis, and we review selected current physical cell targeting technologies engineered to meet these needs: needle and syringe, diffusion patches, liquid jet injectors, and microneedle arrays/patches. We then focus on biolistic particle delivery: we first analyze engineering these systems to meet demanding clinical needs, we then examine the interaction of biolistic devices with the skin, focusing on the mechanical interactions of ballistic impact and cell death, and finally we discuss the current clinical outcomes of one key application of engineered delivery devices--DNA vaccines.

Protective effects of green tea extracts on photoaging and photommunosuppression

OBJECTIVES

This study aimed to investigate whether the sunscreen-containing 2-5% green tea extracts (GTEs) protect ultraviolet irradiation (UVR)-induced photoaging and photoimmunosuppression.

MATERIALS AND METHODS

Twenty volunteers were exposed to repetitive solar-simulated UVR (ssUVR) on the upper back at a dosage of 1.5 minimal erythema doses (MED) per day for four consecutive days. Thirty minutes before each UVR and 6, 24, and 48 h after the last UV exposure, the products containing vehicle, and 2-5% GTEs were applied onto five sites on the dorsal skin, respectively. The skin biopsies were obtained 72 h after the last UVR. The thickness of the stratum corneum and epidermis was measured under the microscope and the expression of cytokeratins (CK)-5/6, CK16, metalloproteinases (MMP)-2, MMP-9, and the CD1a(+) Langerhans cells (LCs) were determined using immunohistochemistry.

RESULTS

Our results showed that UVR substantially induced cutaneous erythema, thickening of the epidermis, overexpression of CK5/6, CK16, MMP-2, MMP-9, and depletion of CD1a(+) LCs. The sunscreens containing different concentrations of GTEs conferred significant protection against the photoaging and photoimmunology-related biological events. Interestingly, the protective effects were not parallel to the concentrations of GTEs, with 2% and 3% GTEs showing the most efficacious photoprotection.

CONCLUSIONS

GTEs-containing sunscreens have potential photoprotective effects on UVR-induced photoaging and photoimmunosuppression.

Characterization of langerhans cells in epidermal sheets along the body of Armadillo (Dasypus novemcinctus)

Armadillos are apparently important reservoirs of Mycobacterium leprae and an animal model for human leprosy, whose immune system has been poorly studied. We aimed at characterizing the armadillo's langerhans cells (LC) using epidermal sheets instead of tissue sections, since the latter restrict analysis only to cut-traversed cells. Epidermal sheets by providing an en face view, are particularly convenient to evaluate dendritic morphology (cells are complete), spatial distribution (regular vs. clustered), and frequency (cell number/tissue area). Lack of anti-armadillo antibodies was overcome using LC-restricted ATPase staining, allowing assessment of cell frequency, cell size, and dendrites extension. Average LC frequency in four animals was 528 LC/mm(2), showing a rather uniform non-clustered distribution, which increased towards the animal's head, while cell size increased towards the tail; without overt differences between sexes. The screening of antibodies to human DC (MHC-II, CD 1a, langerin, CD86) in armadillo epidermal sheets, revealed positive cells with prominent dendritic morphology only with MHC-II and CD86. This allowed us to test DC mobilization from epidermis into dermis under topical oxazolone stimulation, a finding that was corroborated using whole skin conventional sections. We hope that the characterization of armadillo's LC will incite studies of leprosy and immunity in this animal model.

Gender differences in skin: a review of the literature

BACKGROUND

There has been increasing interest in studying gender differences in skin to learn more about disease pathogenesis and to discover more effective treatments. Recent advances have been made in our understanding of these differences in skin histology, physiology, and immunology, and they have implications for diseases such as acne, eczema, alopecia, skin cancer, wound healing, and rheumatologic diseases with skin manifestations.

OBJECTIVE

This article reviews advances in our understanding of gender differences in skin.

METHODS

Using the PubMed database, broad searches for topics, with search terms such as gender differences in skin and sex differences in skin, as well as targeted searches for gender differences in specific dermatologic diseases, such as gender differences in melanoma, were performed. Additional articles were identified from cited references. Articles reporting gender differences in the following areas were reviewed: acne, skin cancer, wound healing, immunology, hair/alopecia, histology and skin physiology, disease-specific gender differences, and psychological responses to disease burden.

RESULTS

A recurring theme encountered in many of the articles reviewed referred to a delicate balance between normal and pathogenic conditions. This theme is highlighted by the complex interplay between estrogens and androgens in men and women, and how changes and adaptations with aging affect the disease process. Sex steroids modulate epidermal and dermal thickness as well as immune system function, and changes in these hormonal levels with aging and/or disease processes alter skin surface pH, quality of wound healing, and propensity to develop autoimmune disease, thereby significantly influencing potential for infection and other disease states. Gender differences in alopecia, acne, and skin cancers also distinguish hormonal interactions as a major target for which more research is needed to translate current findings to clinically significant diagnostic and therapeutic applications.

CONCLUSIONS

The published findings on gender differences in skin yielded many advances in our understanding of cancer, immunology, psychology, skin histology, and specific dermatologic diseases. These advances will enable us to learn more about disease pathogenesis, with the goal of offering better treatments. Although gender differences can help us to individually tailor clinical management of disease processes, it is important to remember that a patient's sex should not radically alter diagnostic or therapeutic efforts until clinically significant differences between males and females arise from these findings. Because many of the results reviewed did not originate from randomized controlled clinical trials, it is difficult to generalize the data to the general population. However, the pressing need for additional research in these areas becomes exceedingly clear, and there is already a strong foundation on which to base future investigations.

Mystery of the disappearing allergen: published allergens rarely seen again

Patch testing is an important tool in the diagnosis of allergic contact dermatitis. Although this technique can be accurate, occasionally the results may be inconclusive. A previously positive result to an allergen may become negative upon repeat testing, and this may complicate the process of achieving a definitive diagnosis. There are some potential explanations for such inconsistencies, including the Excited Skin Syndrome, irritant reactions, a need to repeat the diagnostic algorithm, "rogue" reactions, and "contact allergy." These explanations should be taken into account when interpreting these results. However, further knowledge is needed to solve the mystery of an allergen that subsequently disappears.

Deterioration of the Langerhans cell network of the human gingival epithelium with aging

Dendritic cells (DCs) are the professional antigen-presenting cells responsible for initiating of the immune response. Langerhans cells (LCs) are a type of DC that is a permanent resident of the oral epithelium. LCs are organized conforming a network in such a way as to maximize their surface area for efficient apprehension of antigens. To detect age-related changes in the LCs network, fragments of gingival epithelium spontaneously accompanying dental removals were processed by immunohistochemistry. Monoclonal antibody CD1a followed by biotinized immunoglobulin-streptoavidin peroxidase were used to identify the LCs with the light microscope. LC density and LC types were analyzed according to their morphology and intraepithelial distribution. In the older age group (61-74 years) the density was significantly lower than in the younger age groups. Morphologically, LCs showed fewer dendritic-branching processes and had a rounded shape in the older age group. Present observations indicate that the LC network changes markedly with aging. These results suggest that immunological defense of the oral tissue might be compromised in old age.

Dermatitis de manos

Hand dermatitis is a common skin disease that often has a chronic and relapsing course. Several subtypes of hand dermatitis have been described. In this review, we describe the clinical characteristics of each form of hand eczema, laboratory tests helpful in the diagnosis, and treatment options for this condition.

Engineering of needle-free physical methods to target epidermal cells for DNA vaccination

A challenge in epidermal DNA vaccination is the efficient and targeted delivery of polynucleotides to immunologically sensitive Langerhans cells. This paper investigates this particular challenge for physical delivery approaches. The skin immunology and material properties are examined in the context of the physical cell targeting requirements of the viable epidermis. Selected current physical cell targeting technologies engineered to meet these needs are examined: needle and syringe; diffusion patches; liquid jet injectors; microneedle arrays/patches; and biolistic particle injection. The operating methods and relative performance of these approaches are discussed, with a comment on potential future developments and technologies.

Multiphoton high-resolution 3D imaging of Langerhans cells and keratinocytes in the mouse skin model adopted for epidermal powdered immunization

Langerhans cells (LCs) can be targeted with DNA-coated gold micro-projectiles ("Gene Gun") to induce potent cellular and humoral immune responses. It is likely that the relative volumetric distribution of LCs and keratinocytes within the epidermis impacts on the efficacy of Gene Gun immunization protocols. This study quantified the three-dimensional (3D) distribution of LCs and keratinocytes in the mouse skin model with a near-infrared multiphoton laser-scanning microscope (NIR-MPLSM). Stratum corneum (SC) and viable epidermal thickness measured with MPLSM was found in close agreement with conventional histology. LCs were located in the vertical plane at a mean depth of 14.9 microm, less than 3 mum above the dermo-epidermal boundary and with a normal histogram distribution. This likely corresponds to the fact that LCs reside in the suprabasal layer (stratum germinativum). The nuclear volume of keratinocytes was found to be approximately 1.4 times larger than that of resident LCs (88.6 microm3). Importantly, the ratio of LCs to keratinocytes in mouse ear skin (1:15) is more than three times higher than that reported for human breast skin (1:53). Accordingly, cross-presentation may be more significant in clinical Gene Gun applications than in pre-clinical mouse studies. These interspecies differences should be considered in pre-clinical trials using mouse models.

Tetanus toxoid-loaded transfersomes for topical immunization

Topical immunization is a novel immunization strategy by which antigens and adjuvants are applied topically to intact skin to induce potent antibody and cell-mediated responses. Among various approaches for topical immunization, the vesicular approach is gaining wide attention. Proteineous antigen alone or in combination with conventional bioactive carriers could not penetrate through the intact skin. Hence, specially designed, deformable lipid vesicles called transfersomes were used in this study for the non-invasive delivery of tetanus toxoid (TT). Transfersomes were prepared and characterized for shape, size, entrapment efficiency and deformability index. Fluorescence microscopy was used to investigate the mechanism of vesicle penetration through the skin. The immune stimulating activity of these vesicles was studied by measuring the serum anti-tetanus toxoid IgG titre following topical immunization. The immune response was compared with the same dose of alum adsorbed tetanus toxoid (AATT) given intramuscularly, topically administered plain tetanus toxoid solution, and a physical mixture of tetanus toxoid and transfersomes again given topically. The results indicated that the optimal transfersomal formulation had a soya phosphatidylcholine and sodium deoxycholate ratio of 85:15%, w/w. This formulation showed maximum entrapment efficiency (87.34 +/- 3.81%) and deformability index (121.5 +/- 4.21). An in-vivo study revealed that topically administered tetanus toxoid-loaded transfersomes, after secondary immunization, elicited an immune response (anti-TT-IgG) comparable with that produced by intramuscular AATT. Fluorescence microscopy revealed the penetration of transfersomes through the skin to deliver the antigen to the immunocompetent Langerhans cells.

Epidermal powder immunization: cellular and molecular mechanisms for enhancing vaccine immunogenicity

Epidermal powder immunization (EPI) of mice with an influenza vaccine elicited consistently a higher hemagglutination inhibition (HI) antibody titers than intramuscular (IM) injection using the same dose of vaccine. The epidermal Langerhans cells (LCs) at the site of EPI were found to play an important role in the immune responses. Indeed, depletion of LCs from the immunization site prior to EPI caused a significant reduction in the antibody response. Transfer of LCs isolated from the EPI sites to naive mice induced a robust antigen-specific antibody response. Cytokines produced by target site cells appear to be important for the augmented immune responses induced by EPI. LTR72, a genetically detoxified heat-labile toxin from Escherichia coli with a strong adjuvant effect in EPI, was found to bind the keratinocytes of the epidermis, but not the LCs, and caused the production of elevated TNF-alpha and IL-12 cytokines in emigrating epidermal cells. These results have important implications for the development of a more efficacious human influenza vaccine.

Dermal dendritic cell number correlates with serum autoantibody titers in Brazilian pemphigus foliaceus patients

Pemphigus foliaceus (PF) is an autoimmune bullous disease endemic in Brazil. Since serum IL-12 is increased in patients with PF and Langerhans cells (LC) produce IL-12, we titrated serum autoantibodies by indirect immunofluorescence, and quantified epidermal dendritic cells, known as LC, and dermal dendritic cells (DC). Biopsies of blistering lesions were obtained from 22 patients, 13 of whom were submitted to biopsy of both injured and of apparently healthy skin. The control groups consisted of skin from 8 cadavers and from 12 women submitted to breast plastic surgery. LC and DC were identified with anti-CD1a antibody and quantified by morphometric analysis. LC number in the lesion and in apparently healthy skin from PF patients was similar to that of both control groups. DC number in the injured skin (median=0.94 DC/mm basement membrane) was higher than that of the cadaver group (median=0.13 DC/mm basement membrane). In the 13 patients with biopsies of both injured and apparently healthy skin, LC and DC were present in larger numbers in the lesion. There was a direct correlation between DC number in the lesion of the PF group and serum autoantibody titers. This correlation was not observed for LC number. The increased number of DC in the lesion, as well as its direct correlation with serum autoantibody titers suggest the participation of DC in the pathogenesis of PF. The relationship between increased DC number and IL-12 in PF needs to be clarified.

CD83(+)dendritic cells in the decidua of women with recurrent miscarriage and normal pregnancy

Immunological factors have been postulated to play a role in the aetiology of recurrent miscarriage as the fetus and placenta are semi-allogenic to the mother. Potent immunostimulatory (CD83(+)) dendritic cells have recently been identified in the uterine decidua. This study was conducted to examine whether decidual dendritic cells could play a role in the aetiology of recurrent miscarriage. First trimester placental and decidual biopsies were obtained from 40 women with recurrent miscarriage and 15 gestation-matched normal controls. These biopsies were screened by immunohistochemistry for CD83(+)cells. Staining was analysed by light microscopy and digital image analysis. In both recurrent miscarriage and normal pregnancy, CD83(+)dendritic cells were localized to the decidua. Individual dendritic cells were present in the decidual stroma or in clusters of 3-4 dendritic cells, in lymphoid aggregates. There were no significant differences in decidual CD83(+)dendritic cell density between women with recurrent miscarriage and normal pregnancy when the groups were compared as a whole. However, when segregated by gestational age, decidua from women with recurrent miscarriage at 8 weeks' gestation contained significantly more dendritic cells than gestational age-matched normal controls. This suggests dendritic cells may play a role in the aetiology of some cases of recurrent miscarriage.

Needle-free epidermal powder immunization

Due to the presence of a network of antigen-presenting cells and other cells with innate and adaptive immune functions, the skin is both a sensitive immune organ and a practical target site for vaccine administration. A handful of needle-free immunization technologies have emerged in recent years that aim to take advantage of these characteristics. Skin delivery technologies provide potentially safer alternatives to needle injection and promises increased efficacy in the prevention and/or therapy of infectious diseases, allergic disorders and cancer. In this review, we will cover advances in needle-free skin vaccination technologies and their potential applications to disease prevention and therapy. Emphasis will be placed on epidermal powder immunization and particle-mediated ('gene gun') DNA immunization, which use similar mechanical devices to deliver protein and DNA vaccines, respectively, into the viable epidermis.

Epidermal powder immunization with a recombinant HIV gp120 targets Langerhans cells and induces enhanced immune responses

The recombinant envelope gp120 (rgp120) of human immunodeficiency virus (HIV) is a weak immunogen when administered by intramuscular (IM) injection. In the present study, we report that epidermal powder immunization (EPI) elicits robust antibody responses to the rgp120. EPI of mice with a dose 0.2-5 microg of rgp120 protein elicited geometric mean antibody titers that were 18- to 240-fold higher than that elicited by IM injection using a 5.0 microg dose. Targeting antigen to and mobilization of Langerhans cells (LCs) by EPI may explain the enhanced immunogenicity of the rgp120. EPI with rgp120 using sugar and gold particles as carrier resulted in differential antigen entry into the LCs and differential IgG subclass antibody and cellular immune responses. EPI may serve as a useful tool to evaluate vaccine potential of the rgp120 protein.

Targeting epidermal Langerhans cells by epidermal powder immunization

Immune reactions to foreign or self-antigens lead to protective immunity and, sometimes, immune disorders such as allergies and autoimmune diseases. Antigen presenting cells (APC) including epidermal Langerhans cells (LCs) play an important role in the course and outcome of the immune reactions. Epidermal powder immunization (EPI) is a technology that offers a tool to manipulate the LCs and the potential to harness the immune reactions towards prevention and treatment of infectious diseases and immune disorders.

Epidermal powder immunization induces both cytotoxic T-lymphocyte and antibody responses to protein antigens of influenza and hepatitis B viruses

Cytotoxic T lymphocytes (CTL) play a vital role in host defense against viral and intracellular bacterial infections. However, nonreplicating vaccines administered by intramuscular injection using a syringe and needle elicit predominantly humoral responses and not CTL responses. Here we report that epidermal powder immunization (EPI), a technology that delivers antigens on 1.5- to 2.5-microm gold particles to the epidermis using a needle-free powder delivery system, elicits CTL responses to nonreplicating antigens. Following EPI, a majority of the antigen-coated gold particles were found in the viable epidermis in the histological sections of the target skin. Further studies using transmission electron microscopy revealed the intracellular localization of the gold particles. Many Langerhans cells (LCs) at the vaccination site contained antigen-coated particles, as revealed by two-color immunofluorescence microscopy, and these cells were found in the draining lymph nodes 20 h later. Immune responses to several viral protein antigens after EPI were studied in mice. EPI with hepatitis B surface antigen (HBsAg) and a synthetic peptide of influenza virus nucleoprotein (NP peptide) elicited antigen-specific CTL responses as well as antibody responses. In an in vitro cell depletion experiment, we demonstrated that the CTL activity against HBsAg elicited by EPI was attributed to CD8(+), not CD4(+), T cells. As controls, needle injections of HBsAg or the NP peptide into deeper tissues elicited solely antibody, not CTL, responses. We further demonstrated that EPI with inactivated A/Aichi/68 (H3N2) or A/Sydney/97 (H3N2) influenza virus elicited complete protection against a mouse-adapted A/Aichi/68 virus. In summary, EPI directly delivers protein antigens to the cytosol of the LCs in the skin and elicits both cellular and antibody responses.

Dendritic cells and their role in skin-induced immune responses

This artide gives a brief review on dendritic cells (DC) with regard to their origin, life cyde and functions. The regulation of immune responses by DC functioning as antigen-presenting cells is discussed. Special attention is given to epidermal DC, e.g. Langerhans cells. The perspectives of DC-based therapy are also mentioned.

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.

Huriez syndrome: case report with a detailed analysis of skin dendritic cells

We report a 60-year-old man with familial scleroatrophic syndrome of Huriez who developed squamous cell carcinomas on the affected skin of the right palm. Immunohistochemical analysis showed a marked reduction in the number of CD1a+, Lag+ and S100+ epidermal Langerhans cells, but not of CD1b+ and factor XIIIa+ dermal dendritic cells, limited to palmoplantar skin. The Langerhans cell depletion was not associated with an abnormal skin content of mRNA for factors involved in Langerhans cell development or recruitment in the epidermis, including granulocyte/macrophage colony-stimulating factor, transforming growth factor-beta1 and macrophage inflammatory protein-3alpha. The results indicate that other as yet unknown mechanisms may account for the reduced number of Langerhans cells in the affected skin of such patients.

Quantitative immunohistochemical differences in Langerhans cells in dermatitis due to internal versus external antigen sources

Cutaneous hypersensitivity reactions can develop against antigens delivered through the epidermis (contact dermatitis) or through the blood vessels (e.g., drug eruptions). On routine histology alone, it is not always possible to determine the route of the antigen. Langerhans cells (LC) are the main antigen-presenting cells in contact dermatitis. Dermal dendrocytes (DC) are antigen-presenting cells and may be involved in dermal reactions. We tested the hypothesis that there is a difference between dermatitis due to external and internal antigen sources with regard to the number or function of LC and DC. In 85 cases of dermatitis, numbers of S100 and HLA-DR reactive cells per linear millimetre of epidermis were counted. The amount of epidermal spongiosis was evaluated qualitatively. In 35 cases, the number of DC per mm2 (as defined by Factor XIIIa expression) was evaluated. The patients were then divided into two groups based on whether the final clinical evaluation considered the dermatitis to be secondary to an external (35 cases) or internal antigen (50 cases). Dermatitis due to external antigens had significantly more LC/mm and more frequent HLA-DR expression than dermatitis due to internal antigens, mean +/- SEM; 21.2+/-2.04 vs. 9.1+/-1.02 (p<0.00001) and 16.3+/-2.49 vs. 6.0+/-0.92 (p=0.0001), respectively. Spongiosis was more marked in external antigen cases. DC were more numerous in internal than in external antigen cases, but the differences were not statistically significant. In our model, determination of numbers of LC/mm is the variable with the highest power to discriminate between internal and internal sources. Quantification of HLA-DR+ LC and degree of spongiosis provide little additional discriminatory power.

Effects of topical testosterone propionate on the positive nickel patch test

In a group of nickel sensitized women, we investigated the effects of topical application of testosterone propionate on the epidermic density of CD1 + dendritic cells and on the response to patch tests performed with scaled nickel concentrations. In a significant number of examined subjects, treatment with testosterone propionate induced an increase of the minimum eliciting dose of nickel and an evident reduction of CD1 + dendritic cell epidermic density. In those subjects in which the minimum eliciting dose resulted unmodified, the epidermic density of CD1 + dendritic cells also did not undergo significant variations following treatment with testosterone propionate. This parallelism between the behaviour of the responses to patch tests and the epidermic density of CD1 + dendritic cells induces us to think it possible that testosterone propionate is able to increase the tolerance to contact with allergen by interfering with the activity of Langerhans cells. The possible mechanisms of testosterone action on Langerhans cells remain to be elucidated.

Immunohistochemistry detects differences between lichen planus-like keratosis, lichen planus, and lichenoid actinic keratosis

Lichen planus-like keratosis (LPLK) (benign lichenoid keratosis) is a common skin lesion that shows some morphologic features of lichen planus (LP) and lichenoid actinic keratosis (LAK). To try to detect differences among these three entities, immunohistochemical staining for S100 protein and HLA-DR (with the antibody LN3) was performed in 31 cases of LPLK, 26 of LAK, and 25 of LP. Langerhans cells (LC) were counted per linear mm of epidermis in the S100 and LN3 slides. With anti-S100 staining, LP cases showed higher numbers of LC (mean = 25.3, SE = 2.84, median = 21.2) than did LPLK (mean = 17.3, SE = 2.26, median = 14.5) and LAK (mean = 9.7, SE = 1.5, median = 5.4). With LN3 stains, LP cases also showed higher numbers of LC than did LPLK and LAK. These results suggest that the involvement of LC in the production of lesions may be different in these three entities. However, due to the overlap in distribution of values observed, the use of these stains does not allow a definite diagnosis to be made exclusively based on the number of LC.

Epidermal Langerhans' cells in elderly patients with decubital ulcers

Langerhans' cells in the sacral epidermis 8-10 cm from the lesion of elderly patients (mean age 74 years) with decubital ulcers were studied ultrastructurally and compared with the patients' own normal epidermis from the upper leg, with age-matched normal controls, and with young normal controls (mean age 43 years). High percentages of Langerhans' cells (ranging between 30 and 50%) without dendrites were found in patient epidermis from the sacral region near the lesion and similar percentages in normal skin from the patients' upper leg. In both elderly and young controls, Langerhans' cells without dendrites found in the epidermis of the upper leg were fewer, ranging between 13 and 33%. The density of Langerhans' cells in adjacent sites of the same epidermis was non-homogeneous, being in the range of 0.56-1.19% in patient sacral epidermis, 0.69-1.31% in patient normal leg epidermis, 0.63-4.17% in leg epidermis of the elderly controls, and 0.63-3.94% in leg epidermis of the young controls. The majority of the Langerhans' cells in both patients and controls were located near the basal cell layer and in the mid-epidermis. The percentage of Langerhans' cells found in patient sacral epidermis (0.84 +/- 0.08%) and in their leg epidermis (0.87 +/- 0.15%) was significantly lower than in the elderly controls (1.91 +/- 0.30%) and young controls (1.84 +/- 0.24%). The low percentage of Langerhans' cells in the epidermis of patients with decubital ulcers may affect the healing process of the lesions.

Histology of sun-damaged human skin

In glycomethacrylate sections of sun-exposed skin, we found the epidermis a sensitive index of damage. The stratum corneum of severely damaged skin was often compact and laminated, or gelatinous, and sometimes contained vesicles full of proteinous material. These vesicles arose from the enlarged and distinctly cellular-thick stratum lucidum. Sometimes there was no clear transition between the stratum lucidum and corneum. In the malpighian layer, cell heterogeneity, vacuolization, dysplasia, and zonal necrosis were common. The number of Langerhans cells was reduced in sun-damaged epidermis. The dermis had the usual disparate degrees of elastotic changes, with the formation of amorphous masses and the occurrence of fiber breakdown (fibrorhexis and fibrolysis). Macrophages among the elastotic masses contained coarse granules. When stained by means of the hematoxylin and Lee technique, the elastotic masses in the papillary dermis were pink or red but those in the mid dermis stained lilac to blue; all other elastic fibers stained pink or red. We found reticulin fibers predominantly around the elastotic masses and in areas of fibrorhexis and/or fibrolysis; a delicate collagenous fiber scaffolding supported the elastotic masses.

The immunologic basis of patch testing

During the past decade much has been learned about the cell-mediated immune responses that result in allergic contact dermatitis. The complex interaction between the hapten, the Langerhans cell, the specifically sensitized T cell, and the various soluble mediators of cellular immunity have begun to be delineated. This article reviews the pathophysiology of allergic contact dermatitis. Clinical and physicochemical modulators of this response, such as patient age, the anatomic site of antigenic challenge, and prior treatment with UVB, PUVA, glucocorticoids, or cyclosporine (Cyclosporin A), are stressed. The implications of these findings to the techniques of patch testing are summarized.

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.

Quantification and distribution of lymphocyte subsets and Langerhans cells in normal human oral mucosa and skin

Normal human oral (check) mucosa was studied to discover whether the oral cavity resembles the Mucosal Immune System (MIS) or the Skin Immune System (SIS). Immunophenotypes of lymphocyte subsets and Langerhans cells (LC) with their exact locations in the epithelium and papillary layer of the normal buccal mucosa were determined and compared with data of normal human skin. In a double staining procedure, the distribution of T-lymphocytes in relation to blood and lymph vessels was determined. Immunophenotyping of LC was done with a CD1a monoclonal antibody. In contrast to the skin, T-lymphocytes in buccal mucosa are not primarily perivascular in location. They are more or less randomly distributed on both sides of the basement membrane. The epithelium of the buccal mucosa contains about 37 times as many T-lymphocytes as the epidermis of normal skin. T-cell numbers in the papillary layer are more or less comparable. The CD4/CD8 ratios of about 1/2 in the epithelium of buccal mucosa and 1/4 in the skin indicates preferential presence of the CD8 subset in both sites, but the helper/inducer T-lymphocytes play a much greater role in the epithelium of the buccal mucosa when compared with skin. B-lymphocytes were not found in the epithelium and papillary layer of the buccal mucosa. Thus, immune response associated cells in buccal mucosa do not show the MIS pattern since B cells are absent. It has more in common with SIS but differences are also apparent. In the epithelium of the buccal mucosa the density of LC does not differ significantly from that of the skin, but the papillary layer of the buccal mucosa contains significantly fewer LC than the skin. As in the skin most of the LC of the buccal mucosa are found in the epithelium.

Effect of systemic and topical application of testosterone propionate on the density of epidermal Langerhans cells in the mouse

Epidermal Langerhans cells (LCs) are bone marrow-derived immune cells in the epidermis. Recently, we reported that adenosine triphosphatase (ATPase)-positive LC density in the hind-limb skin of male mice was lower than that of female and that orchiectomy resulted in an increase in LC density, though ovariectomy had no significant effect. To further investigate the control mechanisms of sex differences in LC density, the effect of systemic and topical application of testosterone propionate (TP) on LC density was examined in C57BL/6 mice. Subcutaneous injections of TP 5.8 X 10(-8) mol (20 micrograms)/day/mouse for 14 d resulted in a significant decrease in LC density both in orchiectomized males and normal females, and such an effect was also observed in adrenalectomized mice, suggesting that this effect of TP is not indirectly mediated by glucocorticosteroids. TP was also effective when applied as an ointment (1% or 5%) to the right hind-limb skin of both orchiectomized males and normal females for 14 d; namely, the LC density of the right hind-limb was lower than that of the left. Beta-estradiol and progesterone 5.8 X 10(-8) mol/day/mouse had no significant effect on LC density when systemically applied for 14 d to normal males and females. These results suggest that sex differences in LC density may result from higher concentrations of testosterone or its metabolites in males, and that the function of testosterone may be local.

Rate of Leishmania-induced skin-lesion development in rodents depends on the site of inoculation

Regional differences in the response of mice to infection with three strains of dermotropic Leishmania spp. were shown for skin covering the trunk. Lesions tended to appear earlier and to grow more rapidly on sites over the caudal half of the body than the cranial half, and caudal lesions were more likely than cranial ones to result in metastatic disease in susceptible strains of mice. Site-related variations in lesion development were observed in different strains of mice as well as in golden hamsters. The effect of these regional differences on the development of some parasite-specific, immunological reactions was examined, as were parasite thermosensitivity and location-related variations in host skin temperature as possible explanations.

Sex differences in the densities of epidermal Langerhans cells of the mouse

Cutaneous immune reactions are known to show sexual dimorphism. Langerhans cells (LCs) are bone marrow-derived immune cells in the epidermis and are essential to immune reactions in the skin. In the present research, a study was made of the differences in LC density of male and female mice. Epidermal sheets were separated from the skin of the glabrous part of hind limbs and ears of specific pathogen-free (SPF) mice by ethylenediaminetetraacetic acid (EDTA) treatment and stained for adenosine triphosphatase (ATPase) activity. The density of LCs of hind limb epidermis in male C57BL/6 (823 +/- 20/mm2) and BALB/c (1689 +/- 66/mm2) mice was significantly less than that in females (1363 +/- 52/mm2, p less than 0.001; 2249 +/- 105/mm2, p less than 0.001, respectively). Langerhans cell density in the ears of male C57BL/6 (465 +/- 24/mm2) mice was also significantly less than that in females (542 +/- 17/mm2, p less than 0.02). Although ovariectomy failed to bring about any change in the LC density of hind limb epidermis in female C57BL/6 mice, the LC density in male C57BL/6 mice increased significantly at 4 weeks following orchiectomy (sham operation, 564 +/- 27/mm2; castration, 1179 +/- 49/mm2, p less than 0.001). These results indicate that mouse epidermal LC density depends on sex, i.e., male mice have fewer LCs than female mice. The reduction in LC density in males may possibly be caused by the testis.

Flow cytometric quantification of T6-positive cells in psoriatic epidermis after PUVA and methotrexate therapy

We describe a flow cytometric technique for measuring the percentage of T6-positive cells in suspensions prepared by trypsinization of human epidermis. The value obtained for healthy controls (1.55 +/- 0.52%) corresponds to about 600 T6-positive cells per mm2 of skin surface, a figure in line with histological estimates. No significant change was found in the percentage of T6-positive cells in either the uninvolved or lesional epidermis of untreated psoriatic patients. PUVA treatment resulted in a significant reduction in T6-positive cells. A cyclic fluctuation in the numbers of T6-positive cells was shown to accompany methotrexate administration on a weekly divided dose schedule.

S1 nuclease analysis of alpha-globin gene expression in preleukemic patients with acquired hemoglobin H disease after transfer to mouse erythroleukemia cells

The loss of alpha-globin gene transcriptional activity rarely occurs as an acquired abnormality during the evolution of myeloproliferative disease or preleukemia. To test whether the mutation responsible for the loss of alpha-globin gene expression (hemoglobin H disease) in these patients is linked with the alpha-globin genes on chromosome 16, we transferred chromosome 16 from preleukemic patients with acquired hemoglobin H disease to mouse erythroleukemia cells and measured the transcriptional activity of the human alpha-globin genes. After transfer to mouse erythroleukemia cells, the expression of human alpha-globin genes from the peripheral blood or marrow cells of preleukemic patients with acquired hemoglobin H disease was similar to that of human alpha-globin genes transferred to mouse erythroleukemia cells from normal donors. These data showed that factor(s) in the mouse erythroleukemia cell can genetically complement the alpha-globin gene defect in these preleukemia patients with acquired hemoglobin H disease and suggest that altered expression of a gene in trans to the alpha-globin gene may be responsible for the acquisition of hemoglobin H disease in these patients.

Distribution and turnover of Langerhans cells during delayed immune responses in human skin

The changes in distribution and turnover of T6+ Langerhans cells (LC) in the skin during delayed immune responses to tuberculin, and in the lesions of tuberculoid leprosy and cutaneous Leishmaniasis were investigated. In each situation, there was a dermal accumulation of monocytes and T cells and epidermal thickening with keratinocyte Ia expression. In the tuberculin response a dramatic change in the distribution of LC was observed. By 41 h, T6+ LC were displaced to the upper zone of the thickening epidermis followed by an almost complete loss of LC from the epidermis by approximately 72 h. After 7 d, T6+ cells started to reappear in the epidermis, which regained almost normal numbers of T6+ LC by 14 d. After antigen administration and initiation of the delayed immune response, enhanced numbers of T6+ cells appeared in association with the mononuclear cell infiltrate of the upper dermal lesions. Their numbers peaked by 72 h, were reduced at 7 d, and again enhanced by 14 d, when the epidermis was being repopulated. Similar numbers of T6+ cells were found in the chronic lesions of tuberculoid leprosy and cutaneous Leishmaniasis but not lepromatous leprosy. The cells of the dermis were identified as typical LC by the presence of Birbeck granules and surface T6 antigen at the electron microscope level. These cells were closely associated with lymphocytes. We have quantified the number of LC, evaluated their directional flux into the epidermis and dermis, determined nearest neighbors, and made predictions as to their fate.

Occurrence of donor Langerhans cells in mouse and rat chimeras and their replacement in skin grafts

Evidence is presented that some endogenous Langerhans cells (LCs) may persist indefinitely in skin grafts. This evidence is based on the observation that although 2 weeks after grafting F1 hybrid mice and rats with genetically compatible skin, most of the LCs in the grafts were replaced with those of the host, some LCs of graft origin persisted for as long as the grafts were followed (154 days in mice and 249 days in rats). It has also been demonstrated that the spleen may be as good a source of LCs as the marrow. Thus, 6 weeks after lethally irradiated mice were restored with F1 hybrid spleen cells, most of the LCs in the epidermis of their pinnae were of donor origin. LCs of donor origin also were found in the epidermis of the pinnae of animals that had been inoculated at birth with spleen and lymph node cells (mice) or bone marrow cells (rats). Hence the occurrence of these cells provides another means of confirming that tolerance (chimerism) has been induced.