Lichen planus-like contact dermatitis due to methacrylic acid esters

We report a patient who had lichen planus-like lesions on sites repeatedly exposed to methacrylic acid esters used in the car industry. Histologically, the lesions showed all the features of classical lichen planus. Patch testing revealed positive reactions to methacrylic acid esters in concentrations as low as 5 x 10(-3)%. As dental devices contain methacrylic acid esters, it is possible to speculate that methacrylic acid esters may be one of the causative agents for oral lichen planus.

Dermatoscopic and videomicroscopic features of melanocytic plantar nevi

Nearly 10% of Japanese people have pigmented nevi on the soles. Since malignant melanoma also occurs on the plantar area in the Japanese, it would be very valuable to be able to differentiate benign and malignant lesions in the early clinical state. We have investigated the epiluminescence microscopic features of 500 melanocytic nevi on the soles of Japanese people using a dermatoscope and a videomicroscope that can magnify lesions from x 10 to x 200. The results showed that the surface profile of benign melanocytic nevi is mainly classified into five types; that 9% of plantar nevi, however, do not fit into this classification and are categorized as a miscellaneous type; and that the other nonmelanocytic disorders, such as verruca vulgaris and black heel, are easily differentiated by their surface profile. More important, the histological examination showed that atypical nevi, malignant melanoma in situ, and acral lentiginous melanoma are exclusively compartmentalized in the miscellaneous type of surface profile. Our data suggested that epiluminescence microscopy may be a useful method for discrimination of plantar benign and malignant melanocytic lesions.

Expression of cutaneous lymphocyte-associated antigen defined by monoclonal antibody HECA-452 on human Langerhans cells

Cutaneous lymphocyte-associated antigen (CLA) defined by monoclonal antibody (MoAb) HECA-452 has been shown to be preferentially expressed on cutaneous T cells. The CLA expression has been regarded as a homing molecule of T cells to the skin in various inflammatory cutaneous disorders. In this paper we investigated the significance of CLA expression on Langerhans cells (LC) and found that, in normal skin, some epidermal LC express CLA, and that most dermal CD1a positive cells express CLA. When normal skin was organ cultured, the percentage of CLA positive cells in LC and dermal CD1a positive cells decreased appreciably. In diseased skin, epidermal LC increased in number and most LC expressed CLA. Thus, this study suggests that the CLA expression on LC may play as a homing molecule of LC to the skin.

Colocalization of scavenger receptor in CD68 positive foam cells in verruciform xanthoma

Verruciform xanthoma is a rare variant of xanthoma that appears predominantly on oral mucosa and the anogenital area. The histologic features are characterized by marked accumulation of foam cells in the papillary dermis with verrucous epidermal acanthosis and hyperkeratosis. However, little is known of the nature or origin of foam cells. Recent studies have emphasized the crucial role of macrophage scavenger receptors in the formation of foam cells in atherogenesis. We examined the immunohistologic localization of scavenger receptors in genital verruciform xanthoma. We found that the massively infiltrated foam cells in the papillary dermis were CD68+ monocyte-macrophage lineage cells, and that the majority of CD68+ cells coexpressed scavenger receptors. The in situ staining pattern of scavenger receptor in foam cells was mainly of an intracytoplasmic vacuolar pattern similar to that of dermal resident macrophages found in normal skin. Furthermore, CD1a+ Langerhans cells, completely negative for scavenger receptor, were markedly decreased in number in verruciform xanthoma. These results indicate that scavenger receptor-bearing CD68+ cells are also actively involved in the development of cutaneous verruciform xanthoma, as has been shown to be the case in atherogenesis.

Histopathological evaluation of halo phenomenon in Spitz nevus

We saw a patient with a Spitz nevus surrounded by a halo of depigmentation. Although the halo phenomenon is often seen in pigmented melanocytic nevus, an association of this phenomenon with Spitz nevus seems to be rare. Moreover, histopathological findings showed focal lymphoid infiltration in the epidermis of the depigmented halo and marked infiltration in dermal epithelioid nevus cell nests. Thus, it is suggested that identical mechanisms are involved in the destruction of epidermal melanocytes and dermal nevus cells in halo Spitz nevus.

Up-regulation of CD44 expression by tumor necrosis factor-alpha is neutralized by interleukin-10 in Langerhans cells

CD44 is a principal cell-surface receptor for hyaluronate and is found on a wide variety of cells. CD44 plays an important role in lymphocyte homing, lymphohemopoiesis, and T-cell activation as well as in cell motility and migration. CD44 is expressed on the cell surface of epidermal Langerhans cells (LC), and is one of the candidates for molecules that are involved in the migratory capability of LC, but little is known about its regulatory properties. We examined the modulatory effects of tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 on the CD44 expression in LC. We found 1) that TNF-alpha significantly up-regulated the expression of CD44 in a concentration-dependent manner, 2) that IL-10 down-regulated the expression of CD44 in a concentration-dependent manner, 3) that the effect of TNF-alpha or IL-10 was readily detectable as early as 24 h after the initiation of culture, and 4) that the simultaneous addition of TNF-alpha and IL-10 mutually neutralized the effect of each other. These data suggest that in the epidermal microenvironment the expression of CD44 in LC may be reciprocally regulated by TNF-alpha and IL-10, both of which are known to be produced by surrounding keratinocytes.

Comparative analysis of B7-1 and B7-2 expression in Langerhans cells: differential regulation by T helper type 1 and T helper type 2 cytokines

Epidermal Langerhans cells (LC) are Ia-bearing potent antigen-presenting cells (APC) of dendritic cell lineage that play a crucial role in primary and secondary T cell-dependent immune responses. LC express several costimulatory molecules such as B7, which has been implicated as one of the important determinants of professional APC. Recently, B7 antigens have been shown to include three distinct molecules termed B7-1, B7-2, and B7-3, and the expression of B7-1 and B7-2 in LC has been already confirmed. However, little is known of the regulation of B7-1 and B7-2 expression in LC. We demonstrated that LC do not express B7-1 and B7-2 in situ; however, the expression of both molecules is rapidly induced during the first 3 days of culture, and high levels of expression are maintained at least until day 6. We show that the expression of B7-2 in LC is much higher than that of B7-1 in each experiment, and that B7-1 and B7-2 expression is reproducibly augmented by interleukin (IL)-4 in a dose-dependent manner; however, IL-2 affected expression very little. Finally, B7-1 expression is significantly and dose-dependently down-regulated by interferon (IFN)-gamma or IL-10, and B7-2 expression is consistently inhibited by IL-10, but not by IFN-gamma. The effects of these cytokines are active only in the induction phase (during first 3 days of culture) of B7 expression: the modulatory effects of cytokines are hardly detected in the plateau phase (days 4 to 6 of culture) of B7 expression in LC. These findings suggest that B7-1 and B7-2 expression are indeed selectively and differentially regulated by these T cell-derived cytokines, and that the cytokines may modulate the synthesis of B7 molecules rather than the degradation of already-expressed B7 molecules.

CD44 expression in normal human skin and skin tumors

CD44 is thought to be a principal cell surface receptor for hyaluronic acid. Although the distribution of hyalulonic acid has been studied, little is known about the distribution of the CD44 molecule in the human skin and skin tumors. This study was undertaken to investigate the distribution of the CD44 molecule in normal human skin as well as in benign and malignant skin tumors. In normal skin, CD44 was expressed on 1) keratinocyte cell surfaces throughout the epidermis except for the granular and horny layers, 2) hair follicular cells, 3) eccrine sweat gland cells, and 4) cell surfaces of dendritic cells in the dermis. In skin tumors, although CD44 was expressed on the tumor cell surface of seborreic keratosis, Bowen's disease, and squamous cell carcinoma as in normal skin, we could not detect any CD44 expression on the cell surface of the tumor cells of basal cell carcinoma. However, CD44 positive dendritic cells were observed in the tumor islands of basal cell carcinoma. Phenotypic analysis suggested that these CD44 positive cells were melanocytes.

B7-1 expression of Langerhans cells is up-regulated by proinflammatory cytokines, and is down-regulated by interferon-gamma or by interleukin-10

Langerhans cells (LC) act as potent antigen-presenting cells (APC) for primary and secondary T cell-dependent immune responses. LC express several costimulatory and/or adhesion molecules such as B7/BB1, which has been implicated as one of the important determinants for professional APC. Recent studies have shown that B7/BB1 antigens comprise three distinct molecules termed B7-1, B7-2, and B7-3. We have examined the regulatory properties of B7-1 expression in LC using various cytokines including interleukin (IL)-1 alpha, IL-1 beta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-10, interferon (IFN)-gamma, granulocyte/macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor (TNF)-alpha. We have demonstrated: 1) that the B7-1 expression of LC is reproducibly up-regulated by either GM-CSF, TNF-alpha, IL-1 alpha, IL-1 beta, or IL-4 in a dose- and time-dependent manner, 2) that GM-CSF exhibits the most active effect on B7-1 up-regulation in each experiment, 3) that IFN-gamma or IL-10 profoundly inhibits the B7-1 expression of LC in a dose- and time-dependent manner, and 4) that the down-regulatory ability of IFN-gamma or IL-10 neutralizes the activity of up-regulatory cytokines. The enhancing or inhibitory action of these cytokines on B7-1 expression occurs selectively because none of the cytokines consistently affects I-A expression of LC. These data suggest that the B7-1 expression of LC may be dynamically regulated by these up- and down-regulatory cytokines in normal and inflammatory epidermal microenvironment.

Primary cutaneous CD30(Ki-1)-positive lymphoma of non-T, non-B origin

A 71-year-old Japanese woman had two dome-shaped tumors on her right buttock with several surrounding papules. Histological examination revealed that large anaplastic cells and atypical lymphoid cells densely infiltrated the entire dermis. On immunohistochemical examination, Ki-1, HLA-DR, CD25 (IL-2 receptor alpha), CD122 (IL-2 receptor beta), CD4, CD11c and CD68 were all positive in the tumor cells, whereas CD1a, CD3, CD5, CD8 and CD19 were negative. Neither rearrangement of the T-cell receptor beta, T-cell receptor gamma nor the immunoglobulin heavy-chain was seen. Ultrastructurally, most of the tumor cells contained thick bundles of intermediate filaments in the perinuclear cytoplasm. Thus, this patient was diagnosed as having Ki-1-positive lymphoma of non-T, non-B origin. No recurrence or metastasis of the tumor has been observed in the last 2 years, although surgical resection was required 3 times before control was achieved.

Selective regulation of ICAM-1 and major histocompatibility complex class I and II molecule expression on epidermal Langerhans cells by some of the cytokines released by keratinocytes and T cells

Epidermal Langerhans cells (LC) are major histocompatibility complex (MHC) class II (Ia)-positive dendritic cells that act as potent antigen-presenting or accessory cells for primary and secondary T cell-dependent immune responses. Recent studies have disclosed that the morphological, functional, and phenotypic characteristics of LC are variably and drastically modulated by external stimuli both in vivo and in vitro. However, little is known of the biological significance of diverse cytokines in regulating the surface molecules of LC. To determine the regulatory properties of ICAM-1, Ia, and MHC class I (H-2K) molecules in LC, we have examined the effects of interleukin (IL)-1 alpha, IL-1 beta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-10, interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and granulocyte-macrophage colony-stimulating factor (GM-CSF) on the expression of these molecules. Among the cytokines examined, IFN-gamma markedly and reproducibly up-regulates the expression of H-2K, but not ICAM-1, in Ia+ LC in a time- and dose-dependent manner. TNF-alpha consistently up-regulates the expression of ICAM-1, but not H-2K, in a time- and dose-dependent manner. IL-10 slightly but reproducibly inhibits the expression of ICAM-1, but not H-2K, in a time- and dose-dependent manner. IL-10 potently inhibits the TNF-alpha-induced ICAM-1 up-regulation, but not the IFN-gamma-induced H-2K up-regulation. Moreover, no cytokine consistently affects the Ia expression of LC. In addition, slight enhancing effects have been observed on H-2K expression by IL-4, and on ICAM-1 expression by IL-1 alpha, IL-1 beta, or GM-CSF. The present data suggest that the selective regulation is operative in a certain cell surface moiety of LC by various cytokines. These results further facilitate our understanding of immunobiology of LC.

Interferon-gamma-induced HLA-DR, but not ICAM-1, expression of human keratinocytes is down-regulated by calmodulin antagonist

Interferon-gamma (IFN-gamma) has been shown to induce or enhance the expression of MHC class II and intercellular adhesion molecule-1 (ICAM-1) in a variety of human and murine cell types, including epidermal keratinocytes (KC). However, the expression of MHC class II and ICAM-1 molecules induced by IFN-gamma is not necessarily coordinated. We investigated the inhibitory effects of the calmodulin antagonist, W-7, and its chlorine deficient inactive analogue, W-5, on the expression of MHC class II (HLA-DR) and ICAM-1 by human KC incubated with IFN-gamma. We found that the IFN-gamma-induced expression of HLA-DR was reproducibly and dose-dependently inhibited by W-7. However, the expression of ICAM-1 was highly resistant to the inhibitory effects of W-7. Neither HLA-DR nor ICAM-1 expression was affected by W-5. These data suggest that the IFN-gamma-induced HLA-DR, but not ICAM-1, expression is mediated, if not exclusively, by calmodulin in human KC.

Migration of Thy-1+ dendritic epidermal cells (Thy-1+DEC): Ly48 and TNF-alpha are responsible for the migration of Thy-1+DEC to the epidermis

Thy-1+ dendritic epidermal cells (Thy-1+DEC) are mainly T cells that express T-cell receptor gamma and delta chains with limited diversity of gamma delta, mainly gamma 3 delta 1; such gamma 3 delta 1 TCR-bearing Thy-1+DEC originate from day 16 fetal thymic cells. To understand the migratory capability of Thy-1+DEC, we developed an in vitro model, using skin organ culture. First, emigration of Thy-1+DEC from the epidermis was examined. Ear skin from C3H/He mice was separated into two parts and incubated for 3 d with dermal side down. Thy-1+DEC emigrated from the epidermis into the dermis and then migrated out of the skin into the culture medium. Next, immigration of Thy-1+DEC into the epidermis was examined. Thy-1+DEC were depleted in vivo by daily application of clobetazole propionate solution topically onto the ears of C3H/He mice. Seven days later, ear skin was harvested, separated, and cultured with the dermal side up with syngeneic epidermal cell suspensions with a migration chamber for 3 d. It was found that 1) Thy-1+DEC immigrated into the Thy-1+DEC depleted epidermis as well as into untreated epidermis, and 2) the migratory capability of Thy-1+DEC was directly proved by a biolabeling technique with PKH-26. Blocking studies with various antibodies revealed that leukosialin (S11 monoclonal antibodies) and TNF alpha were important for Thy-1+DEC migration. Thus, Thy-1+DEC retain the potential for migration in vitro, and leukosialin and TNF alpha are partially responsible for the migration of Thy-1+DEC into the epidermis.

Vogt-Koyanagi-Harada's syndrome associated with Hashimoto's thyroiditis

Vogt-Koyanagi-Harada's syndrome has been known as an autoimmune disease which affects the melanocyte-containing tissues. We report a case of Vogt-Koyanagi-Harada's syndrome associated with Hashimoto's thyroiditis. IgM-class antibodies against nevus cells were detected in the patient's serum by indirect immunofluorescence test. These clinical and laboratory findings support the autoimmune theory of this rare syndrome.

Secondary cutaneous oxalosis: cutaneous deposition of calcium oxalate dihydrate after long-term hemodialysis

A 48-year-old Japanese man had miliary calcified papules on the distal fingers after long-term hemodialysis. The crystals in the dermis consisted of calcium oxalate, as revealed by light microscopy and scanning electron microscopy with energy-dispersive x-ray microanalysis. The calcium oxalate was in the form of a dihydrate crystal. Therefore a diagnosis of secondary cutaneous oxalosis was made. In cutaneous oxalosis that occurs as a result of hemodialysis, miliary deposits occur in the fingers, but not the toes, and are present more frequently on the palmar aspects of the fingers. This localization may result from local differences in the metabolism or concentration of calcium or oxalate, or changes in the blood circulation.

Bullous systemic lupus erythematosus with cutaneous mucinosis and leukocytoclastic vasculitis

A 38-year-old man with systemic lupus erythematosus had nodular cutaneous mucinosis, leukocytoclastic vasculitis, and a vesiculobullous eruption. Immunopathologic study of a bullous lesion revealed granular deposits of IgA and IgG along the basement membrane zone. Localization of immune deposits to the lamina and sublamina densa was confirmed by immunoelectron microscopy.

Immunosuppressive effects of azelastine hydrochloride on contact hypersensitivity and T-cell proliferative response: a comparative study with FK-506

Azelastine hydrochloride (AZE) is an anti-allergic drug that inhibits the release of various chemical mediators from mast cells. We compared the immunosuppressive effects of AZE and FK-506 in vivo and in vitro. Topical application of AZE strongly inhibited the efferent phase of contact hypersensitivity, as did application of FK-506. In in vitro experiments, we found that 1) the suppression by AZE on interleukin (IL)-2 production from splenic T cells was partial and considerably large amounts of IL-2 were still produced, even in the presence of 10(-5) M of AZE, which was in sharp contrast to the observed marked inhibition of [3H]-TdR incorporation; 2) AZE significantly inhibited the phorbol myristate acetate-induced IL-2 responsiveness; 3) AZE did not inhibit the IL-2 receptor alpha expression of activated T cells; and 4) the significant inhibitory action was still observed even when AZE was added at 48 h after the initiation of culture. In regard to FK-506, we found that 1) FK-506 completely blocked the production of IL-2; 2) exogeneous IL-2 consistently restored the FK-506-induced inhibition; 3) FK-506 affected the phorbol myristate acetate-induced IL-2 responsiveness very little, if any; and 4) the significant suppression was observed only when FK-506 was added within 24 h after the initiation of culture. Thus, AZE exerts its in vitro immunosuppressive activity preferentially by interfering with the IL-2 responsiveness, with partial inhibition of IL-2 production. Conversely, FK-506 acts as a strong inhibitor of IL-2 production without a prominent effect on IL-2 responsiveness. The immunosuppressive activity of AZE shown in vitro may also be operative in vivo and may be applicable for topical use.

Bilateral periorbital eccrine hidrocystoma

We saw four patients showing identical features as cystic lesions on the bilateral external canthi. Histological examination showed cystic cavities in the dermis. Histological and enzyme histochemical findings suggest that these cystic tumors are of eccrine origin. Thus we diagnosed these cystic tumors as eccrine hidrocystoma with characteristic clinical feature. The recognition of this feature would help to correctly diagnose these eccrine hidrocystoma.

Atopic dermatitis--immunological abnormality and its background

The production of IgE is mainly regulated by cognate and/or non-cognate interaction between B cells and T cells. Two types of helper T cells are recognized in the murine system, Th1 and Th2, by the type of cytokine they produce. Several lines of evidence disclosed that unbalanced generation of Th2/Th1-like cells occurs in atopic disorders, such as atopic dermatitis, in which a high level of serum IgE is found in the majority of patients. Analysis of skin-derived immunocompetent cells, such as Langerhans cells and T cells, has provided us with a new understanding of the pathophysiology of atopic dermatitis. The recent progress in immunological aspects of atopic dermatitis is reviewed.

Immunotherapy for Stewart-Treves syndrome. Usefulness of intrapleural administration of tumor-infiltrating lymphocytes against massive pleural effusion caused by metastatic angiosarcoma

We describe a 56-year-old woman with Stewart-Treves syndrome who had severe dyspnea from a pleural effusion caused by metastatic angiosarcoma in the right lung. Tumor-infiltrating lymphocytes (TIL) in the pleural effusion were cultured and expanded in vitro in the continuous presence of recombinant interleukin 2 with periodic stimulation by CD3 antibody. The expanded TIL were administered intrapleurally seven times at 1- to 4-week intervals in combination with intravenous infusion of recombinant interleukin 2. A panel of T-cell clones was also obtained from TIL. Immunotherapy dramatically improved the patient's dyspnea and pleural effusion. A CD4+ T-cell clone and a CD8+ T-cell clone established from TIL had specific cytotoxicity to the tumor cells.

Serum soluble IL-2 receptor (sIL-2R) and eosinophil cationic protein (ECP) levels in atopic dermatitis

We examined the serum soluble IL-2 receptor and eosinophil cationic protein levels in patients with atopic dermatitis (n = 21), patients with urticaria (n = 12), and normal healthy individuals (n = 14). We found that both soluble IL-2 receptor levels and eosinophil cationic protein levels were significantly higher in atopic dermatitis than in urticaria or normal controls. Although both soluble IL-2 receptor levels and eosinophil cationic protein levels were significantly correlated with clinical severity scores in atopic dermatitis, the correlation between eosinophil cationic protein levels and clinical severity scores was higher than that between soluble IL-2 receptor levels and clinical severity scores. However, soluble IL-2 receptor levels, eosinophil cationic protein levels and clinical severity scores were not significantly correlated with IgE levels. The chronological changes of soluble IL-2 receptor and eosinophil cationic protein levels differ from patient to patient. However, levels of soluble IL-2 receptor and eosinophil cationic protein seem to parallel to each other in 65% of patients with AD. Measurement of serum eosinophil cationic protein or soluble IL-2 receptor levels may be a useful tool to monitor the short-term or long-term disease activity of atopic dermatitis in conjunction with clinical severity scores.

Altered expression of NU-T2-BMZ antigen and type VII collagen in basal cell epithelioma

The cutaneous basement membrane zone (BMZ) is composed of a large number of molecular components. We have recently reported that one of the CD1b monoclonal antibodies (MoAb), NU-T2, reacts to the BMZ of the normal human skin, esophagus and stomach. In order to further elucidate the biological properties of the NU-T2-BMZ antigen, we investigated the expression of NU-T2-BMZ antigen and type VII collagen (well identified component of anchoring fibrils) in various skin tumors such as basal cell epithelioma (BCE), squamous cell carcinoma, Bowen's disease, actinic keratosis and seborrheic keratosis. NU-T2 MoAb failed to react to the BMZ in all BCE. Anti-type VII collagen MoAb showed reduced staining of the BMZ in some nests of BCE. Both antigens, however, were preserved in the BMZ of other skin tumors as in the normal adjacent skin. Furthermore, anti-type VII collagen MoAb demonstrated the clear intratumoral staining in all BCE examined. The abnormal expression of NU-T2-BMZ antigen and type VII collagen may partly explain the space formation between the BCE nests and the surrounding stroma frequently observed in histology.

Quantitative determination of human aldose reductase by enzyme-linked immunosorbent assay. Immunoassay of human aldose reductase

An antibody-sandwich enzyme-linked immunosorbent assay (ELISA) for evaluating tissue levels of aldose reductase was developed using a polyclonal antibody prepared against the recombinant enzyme expressed in a baculovirus system. The specificity of this antibody to aldose reductase was verified by immunoprecipitation, immunoblotting and ELISA. The polyclonal antibody did not crossreact with human aldehyde reductase, an enzyme in the same aldo-keto reductase family structurally and functionally related to aldose reductase. The sensitivity and specificity of this assay method enabled direct determination of aldose reductase level in various human tissues including the erythrocyte. The highest level of aldose reductase was detected in the kidney medulla among tissues investigated. More than a 2-fold variability in the erythrocyte aldose reductase was demonstrated among healthy individuals, indicating the heterogeneity of this enzyme expression in a human population. This assay system may be useful for direct measurement of the level of tissue aldose reductase in conjunction with the evaluation of the efficacy of aldose reductase inhibitors prescribed for the treatment of diabetic complications.

Amelanotic metastatic melanoma in a patient with oculocutaneous albinism

Melanomas are rare in patients who have albinism, compared with the frequent occurrence of squamous cell carcinomas and basal cell carcinomas. This report describes amelanotic metastatic melanoma in a 58-year-old Japanese man who had tyrosinase-positive oculocutaneous albinism. A prolonged bleeding time, facioscapulohumeral muscular dystrophy, and Gilbert syndrome were also present. Superficial spreading melanoma with evidence of spontaneous regression on his right forearm was suspected as a possible primary site. Twenty-two cases of melanomas in persons who have albinism have been reported.

[Skin disorders with eosinophilia]

Many inflammatory or neoplastic dermatologic disorders have been recognized to be associated with tissue and/or blood eosinophilia. Furthermore, the degree of local and accompanying blood eosinophilia usually reflect the intensity and extent of the disease activity in various skin disorders. Recent advancement in the biology of eosinophils have also clarified the pathogenetic role of eosinophils in some diseases. In this issue, the dermatologic disorders with eosinophilia are reviewed.

Epitope mapping of CD1a, CD1b, and CD1c antigens in human skin: differential localization on Langerhans cells, keratinocytes, and basement membrane zone

CD1 antigens are classified into at least three groups, CD1a, CD1b, and CD1c. In order to delineate the localization of epitopes of CD1 antigens in human skin, we examined the immunoreactivity of fourteen different CD1 antibodies (seven CD1a, five CD1b, and two CD1c antibodies). The epitopes for CD1a, CD1b, and CD1c are differentially localized on epidermal Langerhans cells, dermal dendritic cells, keratinocytes, the luminal portion of eccrine gland ducts, and the basement membrane zone in normal human skin.

Simple epithelial cytokeratin-expression in seborrheic keratosis

The cytokeratin expression of seborrheic keratosis was studied by means of immunohistochemistry and compared with that of normal human skin. The following findings were obtained in seborrheic keratosis: (1) a partial lack of high molecular weight cytokeratin (#1/68 kD, #10/56.6 kD) in all ten cases examined; (2) the detection of cytokeratin typical for simple epithelia (#8/52.5 kD, #18/45 kD, #19/40 kD) in eight of ten cases; and (3) the detection of cytokeratin #5/58 kD in suprabasal cells in 5 of 10 cases. An immunoelectron-microscopic investigation, using an anti-keratin antibody against cytokeratin #19/40 kD, revealed a whirl-like arrangement of keratin filaments within immunoreactive cells, in contrast to a linear, parallel arrangement in non-immunoreactive cells. Cells known to express cytokeratin typical for simple epithelia, such as sweat gland cells or Merkel cells, were not observed. The altered cytokeratin gene-expression in seborrheic keratosis may be attributable to de-differentiation of tumor cells or potential re-differentiation towards embryonic keratinocytes.