Langerhans Cells: Recirculating, dendritic, antigen-presenting cells containing characteristic racket-shaped granules (Birbeck granules). They are found principally in the stratum spinosum of the EPIDERMIS and are rich in Class II MAJOR HISTOCOMPATIBILITY COMPLEX molecules. Langerhans cells were the first dendritic cell to be described and have been a model of study for other dendritic cells (DCs), especially other migrating DCs such as dermal DCs and INTERSTITIAL DENDRITIC CELLS.Histiocytosis, Langerhans-Cell: A group of disorders resulting from the abnormal proliferation of and tissue infiltration by LANGERHANS CELLS which can be detected by their characteristic Birbeck granules (X bodies), or by monoclonal antibody staining for their surface CD1 ANTIGENS. Langerhans-cell granulomatosis can involve a single organ, or can be a systemic disorder.Islets of Langerhans: Irregular microscopic structures consisting of cords of endocrine cells that are scattered throughout the PANCREAS among the exocrine acini. Each islet is surrounded by connective tissue fibers and penetrated by a network of capillaries. There are four major cell types. The most abundant beta cells (50-80%) secrete INSULIN. Alpha cells (5-20%) secrete GLUCAGON. PP cells (10-35%) secrete PANCREATIC POLYPEPTIDE. Delta cells (~5%) secrete SOMATOSTATIN.Epidermis: The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of EPITHELIUM: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis).Mannose-Binding Lectins: A subclass of lectins that are specific for CARBOHYDRATES that contain MANNOSE.Langerhans Cell Sarcoma: Rare malignant neoplasm of dendritic LANGERHANS CELLS exhibiting atypical cytology, frequent mitoses, and aggressive clinical behavior. They can be distinguished from other histiocytic and dendritic proliferations by immunohistochemical and ultrastructure studies. Cytologically benign proliferations of Langerhans cells are called LANGERHANS CELL HISTIOCYTOSIS.Skin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Dermatitis, Contact: A type of acute or chronic skin reaction in which sensitivity is manifested by reactivity to materials or substances coming in contact with the skin. It may involve allergic or non-allergic mechanisms.Antigens, CD1: Glycoproteins expressed on cortical thymocytes and on some dendritic cells and B-cells. Their structure is similar to that of MHC Class I and their function has been postulated as similar also. CD1 antigens are highly specific markers for human LANGERHANS CELLS.Eosinophilic Granuloma: The most benign and common form of Langerhans-cell histiocytosis which involves localized nodular lesions predominantly of the bones but also of the gastric mucosa, small intestine, lungs, or skin, with infiltration by EOSINOPHILS.Dendritic Cells: Specialized cells of the hematopoietic system that have branch-like extensions. They are found throughout the lymphatic system, and in non-lymphoid tissues such as SKIN and the epithelia of the intestinal, respiratory, and reproductive tracts. They trap and process ANTIGENS, and present them to T-CELLS, thereby stimulating CELL-MEDIATED IMMUNITY. They are different from the non-hematopoietic FOLLICULAR DENDRITIC CELLS, which have a similar morphology and immune system function, but with respect to humoral immunity (ANTIBODY PRODUCTION).Lectins, C-Type: A class of animal lectins that bind to carbohydrate in a calcium-dependent manner. They share a common carbohydrate-binding domain that is structurally distinct from other classes of lectins.Dermis: A layer of vascularized connective tissue underneath the EPIDERMIS. The surface of the dermis contains innervated papillae. Embedded in or beneath the dermis are SWEAT GLANDS; HAIR FOLLICLES; and SEBACEOUS GLANDS.Antigens, CD: Differentiation antigens residing on mammalian leukocytes. CD stands for cluster of differentiation, which refers to groups of monoclonal antibodies that show similar reactivity with certain subpopulations of antigens of a particular lineage or differentiation stage. The subpopulations of antigens are also known by the same CD designation.Mice, Inbred BALB CCell Movement: The movement of cells from one location to another. Distinguish from CYTOKINESIS which is the process of dividing the CYTOPLASM of a cell.Dinitrofluorobenzene: Irritants and reagents for labeling terminal amino acid groups.Histiocytosis: General term for the abnormal appearance of histiocytes in the blood. Based on the pathological features of the cells involved rather than on clinical findings, the histiocytic diseases are subdivided into three groups: HISTIOCYTOSIS, LANGERHANS CELL; HISTIOCYTOSIS, NON-LANGERHANS-CELL; and HISTIOCYTIC DISORDERS, MALIGNANT.Antigens, Surface: Antigens on surfaces of cells, including infectious or foreign cells or viruses. They are usually protein-containing groups on cell membranes or walls and may be isolated.Haptens: Small antigenic determinants capable of eliciting an immune response only when coupled to a carrier. Haptens bind to antibodies but by themselves cannot elicit an antibody response.Dermatitis, Allergic Contact: A contact dermatitis due to allergic sensitization to various substances. These substances subsequently produce inflammatory reactions in the skin of those who have acquired hypersensitivity to them as a result of prior exposure.Keratinocytes: Epidermal cells which synthesize keratin and undergo characteristic changes as they move upward from the basal layers of the epidermis to the cornified (horny) layer of the skin. Successive stages of differentiation of the keratinocytes forming the epidermal layers are basal cell, spinous or prickle cell, and the granular cell.Dermatitis, Photoallergic: A delayed hypersensitivity involving the reaction between sunlight or other radiant energy source and a chemical substance to which the individual has been previously exposed and sensitized. It manifests as a papulovesicular, eczematous, or exudative dermatitis occurring chiefly on the light-exposed areas of the skin.Cell Count: The number of CELLS of a specific kind, usually measured per unit volume or area of sample.Histocompatibility Antigens Class II: Large, transmembrane, non-covalently linked glycoproteins (alpha and beta). Both chains can be polymorphic although there is more structural variation in the beta chains. The class II antigens in humans are called HLA-D ANTIGENS and are coded by a gene on chromosome 6. In mice, two genes named IA and IE on chromosome 17 code for the H-2 antigens. The antigens are found on B-lymphocytes, macrophages, epidermal cells, and sperm and are thought to mediate the competence of and cellular cooperation in the immune response. The term IA antigens used to refer only to the proteins encoded by the IA genes in the mouse, but is now used as a generic term for any class II histocompatibility antigen.Lymph Nodes: They are oval or bean shaped bodies (1 - 30 mm in diameter) located along the lymphatic system.Flushing: A transient reddening of the face that may be due to fever, certain drugs, exertion, stress, or a disease process.Skin Diseases, Viral: Skin diseases caused by viruses.Antigen Presentation: The process by which antigen is presented to lymphocytes in a form they can recognize. This is performed by antigen presenting cells (APCs). Some antigens require processing before they can be recognized. Antigen processing consists of ingestion and partial digestion of the antigen by the APC, followed by presentation of fragments on the cell surface. (From Rosen et al., Dictionary of Immunology, 1989)Chemokine CCL20: A CC-type chemokine with specificity for CCR6 RECEPTORS. It has activity towards DENDRITIC CELLS; T-LYMPHOCYTES; and B-LYMPHOCYTES.Histiocytes: Macrophages found in the TISSUES, as opposed to those found in the blood (MONOCYTES) or serous cavities (SEROUS MEMBRANE).Xanthogranuloma, Juvenile: Benign disorder of infants and children caused by proliferation of HISTIOCYTES, macrophages found in tissues. These histiocytes, usually lipid-laden non-Langerhans cells, form multiple yellow-red nodules most often in the skin, the eye, and sometimes in the viscera. Patients appear to have normal lipid metabolism and are classified as a normolipemic non-Langerhans cell histiocytosis.Injections, Intradermal: The forcing into the skin of liquid medication, nutrient, or other fluid through a hollow needle, piercing the top skin layer.Cell Differentiation: Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs.Oxazolone: Immunologic adjuvant and sensitizing agent.Picryl Chloride: A hapten that generates suppressor cells capable of down-regulating the efferent phase of trinitrophenol-specific contact hypersensitivity. (Arthritis Rheum 1991 Feb;34(2):180).Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Mice, Inbred C57BLT-Lymphocytes: Lymphocytes responsible for cell-mediated immunity. Two types have been identified - cytotoxic (T-LYMPHOCYTES, CYTOTOXIC) and helper T-lymphocytes (T-LYMPHOCYTES, HELPER-INDUCER). They are formed when lymphocytes circulate through the THYMUS GLAND and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen.Islets of Langerhans Transplantation: The transference of pancreatic islets within an individual, between individuals of the same species, or between individuals of different species.Ultraviolet Rays: That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants.Dinitrochlorobenzene: A skin irritant that may cause dermatitis of both primary and allergic types. Contact sensitization with DNCB has been used as a measure of cellular immunity. DNCB is also used as a reagent for the detection and determination of pyridine compounds.Antigens, CD86: A costimulatory ligand expressed by ANTIGEN-PRESENTING CELLS that binds to CD28 ANTIGEN with high specificity and to CTLA-4 ANTIGEN with low specificity. The interaction of CD86 with CD28 ANTIGEN provides a stimulatory signal to T-LYMPHOCYTES, while its interaction with CTLA-4 ANTIGEN may play a role in inducing PERIPHERAL TOLERANCE.Antigen-Presenting Cells: A heterogeneous group of immunocompetent cells that mediate the cellular immune response by processing and presenting antigens to the T-cells. Traditional antigen-presenting cells include MACROPHAGES; DENDRITIC CELLS; LANGERHANS CELLS; and B-LYMPHOCYTES. FOLLICULAR DENDRITIC CELLS are not traditional antigen-presenting cells, but because they hold antigen on their cell surface in the form of IMMUNE COMPLEXES for B-cell recognition they are considered so by some authors.Fluorescein-5-isothiocyanate: Fluorescent probe capable of being conjugated to tissue and proteins. It is used as a label in fluorescent antibody staining procedures as well as protein- and amino acid-binding techniques.Dermatitis: Any inflammation of the skin.Skin DiseasesVulvar Diseases: Pathological processes of the VULVA.Chemokine CCL17: A CC-type chemokine that is found at high levels in the THYMUS and has specificity for CCR4 RECEPTORS. It is synthesized by DENDRITIC CELLS; ENDOTHELIAL CELLS; KERATINOCYTES; and FIBROBLASTS.Ultraviolet Therapy: The use of ultraviolet electromagnetic radiation in the treatment of disease, usually of the skin. This is the part of the sun's spectrum that causes sunburn and tanning. Ultraviolet A, used in PUVA, is closer to visible light and less damaging than Ultraviolet B, which is ionizing.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.Mucous Membrane: An EPITHELIUM with MUCUS-secreting cells, such as GOBLET CELLS. It forms the lining of many body cavities, such as the DIGESTIVE TRACT, the RESPIRATORY TRACT, and the reproductive tract. Mucosa, rich in blood and lymph vessels, comprises an inner epithelium, a middle layer (lamina propria) of loose CONNECTIVE TISSUE, and an outer layer (muscularis mucosae) of SMOOTH MUSCLE CELLS that separates the mucosa from submucosa.Chemokines, CC: Group of chemokines with adjacent cysteines that are chemoattractants for lymphocytes, monocytes, eosinophils, basophils but not neutrophils.HLA-DR Antigens: A subclass of HLA-D antigens that consist of alpha and beta chains. The inheritance of HLA-DR antigens differs from that of the HLA-DQ ANTIGENS and HLA-DP ANTIGENS.Immunophenotyping: Process of classifying cells of the immune system based on structural and functional differences. The process is commonly used to analyze and sort T-lymphocytes into subsets based on CD antigens by the technique of flow cytometry.Antigens, CD80: A costimulatory ligand expressed by ANTIGEN-PRESENTING CELLS that binds to CTLA-4 ANTIGEN with high specificity and to CD28 ANTIGEN with low specificity. The interaction of CD80 with CD28 ANTIGEN provides a costimulatory signal to T-LYMPHOCYTES, while its interaction with CTLA-4 ANTIGEN may play a role in inducing PERIPHERAL TOLERANCE.Antigens, CD14: Glycolipid-anchored membrane glycoproteins expressed on cells of the myelomonocyte lineage including monocytes, macrophages, and some granulocytes. They function as receptors for the complex of lipopolysaccharide (LPS) and LPS-binding protein.Flow Cytometry: Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake.Dermatitis, Atopic: A chronic inflammatory genetically determined disease of the skin marked by increased ability to form reagin (IgE), with increased susceptibility to allergic rhinitis and asthma, and hereditary disposition to a lowered threshold for pruritus. It is manifested by lichenification, excoriation, and crusting, mainly on the flexural surfaces of the elbow and knee. In infants it is known as infantile eczema.Lymphocyte Activation: Morphologic alteration of small B LYMPHOCYTES or T LYMPHOCYTES in culture into large blast-like cells able to synthesize DNA and RNA and to divide mitotically. It is induced by INTERLEUKINS; MITOGENS such as PHYTOHEMAGGLUTININS, and by specific ANTIGENS. It may also occur in vivo as in GRAFT REJECTION.Granulocyte-Macrophage Colony-Stimulating Factor: An acidic glycoprotein of MW 23 kDa with internal disulfide bonds. The protein is produced in response to a number of inflammatory mediators by mesenchymal cells present in the hemopoietic environment and at peripheral sites of inflammation. GM-CSF is able to stimulate the production of neutrophilic granulocytes, macrophages, and mixed granulocyte-macrophage colonies from bone marrow cells and can stimulate the formation of eosinophil colonies from fetal liver progenitor cells. GM-CSF can also stimulate some functional activities in mature granulocytes and macrophages.Antigens, CD34: Glycoproteins found on immature hematopoietic cells and endothelial cells. They are the only molecules to date whose expression within the blood system is restricted to a small number of progenitor cells in the bone marrow.Organ Culture Techniques: A technique for maintenance or growth of animal organs in vitro. It refers to three-dimensional cultures of undisaggregated tissue retaining some or all of the histological features of the tissue in vivo. (Freshney, Culture of Animal Cells, 3d ed, p1)Microscopy, Electron: Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.Cytoplasmic Granules: Condensed areas of cellular material that may be bounded by a membrane.Administration, Cutaneous: The application of suitable drug dosage forms to the skin for either local or systemic effects.Receptors, CCR6: CCR receptors with specificity for CHEMOKINE CCL20. They are expressed at high levels in T-LYMPHOCYTES; B-LYMPHOCYTES; and DENDRITIC CELLS.Biolistics: Techniques where DNA is delivered directly into organelles at high speed using projectiles coated with nucleic acid, shot from a helium-powered gun (gene gun). One of these techniques involves immunization by DNA VACCINES, which delivers DNA-coated gold beads to the epidermis.Orbital Diseases: Diseases of the bony orbit and contents except the eyeball.Administration, Topical: The application of drug preparations to the surfaces of the body, especially the skin (ADMINISTRATION, CUTANEOUS) or mucous membranes. This method of treatment is used to avoid systemic side effects when high doses are required at a localized area or as an alternative systemic administration route, to avoid hepatic processing for example.Antigens, CD11c: An integrin alpha subunit of approximately 150-kDa molecular weight. It is expressed at high levels on monocytes and combines with CD18 ANTIGEN to form the cell surface receptor INTEGRIN ALPHAXBETA2. The subunit contains a conserved I-domain which is characteristic of several of alpha integrins.Antibodies, Monoclonal: Antibodies produced by a single clone of cells.Membrane Glycoproteins: Glycoproteins found on the membrane or surface of cells.Cornea: The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed)Mice, Transgenic: Laboratory mice that have been produced from a genetically manipulated EGG or EMBRYO, MAMMALIAN.Bone Diseases: Diseases of BONES.Blister: Visible accumulations of fluid within or beneath the epidermis.Osmium Tetroxide: (T-4)-Osmium oxide (OsO4). A highly toxic and volatile oxide of osmium used in industry as an oxidizing agent. It is also used as a histological fixative and stain and as a synovectomy agent in arthritic joints. Its vapor can cause eye, skin, and lung damage.CD4-Positive T-Lymphocytes: A critical subpopulation of T-lymphocytes involved in the induction of most immunological functions. The HIV virus has selective tropism for the T4 cell which expresses the CD4 phenotypic marker, a receptor for HIV. In fact, the key element in the profound immunosuppression seen in HIV infection is the depletion of this subset of T-lymphocytes.Antigens, CD40: A member of the tumor necrosis factor receptor superfamily with specificity for CD40 LIGAND. It is found on mature B-LYMPHOCYTES and some EPITHELIAL CELLS, lymphoid DENDRITIC CELLS. Evidence suggests that CD40-dependent activation of B-cells is important for generation of memory B-cells within the germinal centers. Mutations of the gene for CD40 antigen result in HYPER-IGM IMMUNODEFICIENCY SYNDROME, TYPE 3. Signaling of the receptor occurs through its association with TNF RECEPTOR-ASSOCIATED FACTORS.Skin Transplantation: The grafting of skin in humans or animals from one site to another to replace a lost portion of the body surface skin.Tumor Necrosis Factor-alpha: Serum glycoprotein produced by activated MACROPHAGES and other mammalian MONONUCLEAR LEUKOCYTES. It has necrotizing activity against tumor cell lines and increases ability to reject tumor transplants. Also known as TNF-alpha, it is only 30% homologous to TNF-beta (LYMPHOTOXIN), but they share TNF RECEPTORS.Gene Knock-In Techniques: Techniques used to add in exogenous gene sequence such as mutated genes; REPORTER GENES, to study mechanisms of gene expression; or regulatory control sequences, to study effects of temporal changes to GENE EXPRESSION.Cautery: The application of a caustic substance, a hot instrument, an electric current, or other agent to control bleeding while removing or destroying tissue.Cytokines: Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner.Monocytes: Large, phagocytic mononuclear leukocytes produced in the vertebrate BONE MARROW and released into the BLOOD; contain a large, oval or somewhat indented nucleus surrounded by voluminous cytoplasm and numerous organelles.Poisons: Substances which, when ingested, inhaled, or absorbed, or when applied to, injected into, or developed within the body in relatively small amounts may, by their chemical action, cause damage to structure or disturbance of function. (From Dorland, 27th ed)Betamethasone Valerate: The 17-valerate derivative of BETAMETHASONE. It has substantial topical anti-inflammatory activity and relatively low systemic anti-inflammatory activity.Hypersensitivity, Delayed: An increased reactivity to specific antigens mediated not by antibodies but by cells.Lymphatic System: A system of organs and tissues that process and transport immune cells and LYMPH.