Kozo Yoneda

The monoclonal antibody DCGM4 recognizes Langerin, a protein specific of Langerhans cells, and is rapidly internalized from the cell surface

We generated monoclonal antibody (mAb) DCGM4 by immunization with human dendritic cells (DC) from CD34+ progenitors cultured with granulocyte‐macrophage colony‐stimulating factor and TNF‐α. mAb DCGM4 was selected for its reactivity with a cell surface epitope present only on a subset of DC. Reactivity was strongly enhanced by the Langerhans cell (LC) differentiation factor TGF‐β and down‐regulated by CD40 ligation. mAb DCGM4 selectively stained LC, hence we propose that the antigen be termed Langerin. mAb DCGM4 also stained intracytoplasmically, but neither colocalized with MHC class II nor with lysosomal LAMP‐1 markers. Notably, mAb DCGM4 was rapidly internalized at 37 °C, but did not gain access to MHC class II compartments. Finally, Langerin was immunoprecipitated as a 40‐kDa protein with a pI of 5.2 – 5.5. mAb DCGM4 will be useful to further characterize Langerin, an LC‐restricted molecule involved in routing of cell surface material in immature DC.

FRACTALKINE AND MACROPHAGE-DERIVED CHEMOKINE : T CELL-ATTRACTING CHEMOKINES EXPRESSED IN T CELL AREA DENDRITIC CELLS

Dendritic cells (DC) are a system of antigen‐presenting cells specialized in interaction with T cells. Recently it has been reported that DC can produce CC (β) chemokines that attract T cells. In this study we isolated mouse fractalkine and macrophage‐derived chemokine (MDC) belonging to CX3C (δ) and CC chemokine families, respectively, from bone marrow‐derived mature DC. While expression of fractalkine, which has so far been only examined in the brain and in vitro endothelial cells so far, was rather ubiquitous, MDC, which has been reported to be synthesized by macrophages and DC, was expressed specifically in the thymus and lymphnode. This is the first report that indicates fractalkine expression by DC. Expression of fractalkine and MDC mRNA increased with maturation of DC during in vitro culture of bone marrow cells. Spleen‐ and epidermis‐derived mature DC in culture also expressed these chemokines. Furthermore, their expression was detected selectively by Northern hybridization in CD11c+ B220– DC freshly purified from lymph nodes, and in large stellate cells in the lymph node T cell areas by in situ hybridization. Conditioned media of 293T cells transfected with these chemokine cDNA were chemotactic to Con A‐activated splenic T cells as well as the mouse T cell line EL4. In conclusion, while fractalkine and MDC belong to different families of chemokines, both may be involved in recruitment of T cells for interaction with mature DC in the immune response.

Monocyte-derived dendritic cells have a phenotype comparable to that of dermal dendritic cells and display ultrastructural granules distinct from Birbeck granules.

Most monocyte‐derived dendritic cells (DC) display CD1a, like Langerhans cells (LC) and some dermal DC, but their relationship with these skin DC remains unclear. To address this issue, we studied the expression of different antigens characteristic of skin DC and of monocyte/macrophages in CD1a+ and CD1a– monocyte‐derived DC. Their phenotype indicated that they may be related to dermal DC rather than to LC, i.e., they were all CD11b‐positive, and 72% were Factor XIIIa‐positive, but they did not express E‐cadherin nor VLA‐6. It is interesting that CD1a+ and CD1a– cells showed intracytoplasmic granules that were different from LC Birbeck granules. These pheno‐typical and ultrastructural features are comparable to those of CD14‐derived DC obtained from cord blood precursors [C. Caux et al. J. Exp. Med. 184, 695–706]. These results show a close relationship between these two in vitro models, which are both related to dermal DC. J. Leukoc. Biol. 64: 484–493; 1998.

Spontaneous regression of Merkel cell carcinoma: a comparative study of TUNEL index and tumor-infiltrating lymphocytes between spontaneous regression and non-regression group

Some Merkel cell carcinomas (MCC) have been reported to regress spontaneously. To clarify the mechanisms of spontaneous regression (SR) of MCC, we analyzed the TUNEL index, the labeling index of proliferating cell nuclear antigen (PCNA), the labeling index of bcl-2 protein, and the expression of p53 of the tumor cells. We also evaluated the number of infiltrating lymphocytes surrounding the tumor in the tissue specimens. Among seven patients with MCC (SR: n=4; non-regression (NR): n=3), the TUNEL index in the SR group was significantly higher than that in NR group (5.2 and 2.0%, respectively). In addition, the number of lymphocytes around the tumor nests was also significantly increased in the SR group compared to NR group (1576 and 663 cells/mm(2), respectively). Most of the infiltrating lymphocytes were UCHL-1 positive T-cells. There were no significant differences of the PCNA labeling index, the bcl-2 protein labeling index, and the expression p53 between SR and NR group. These results indicate that apoptosis and local T-cell mediated immune response might be involved in spontaneous regression of MCC.

Melanoma in situ of the penis

Melanoma of the penis is rare and the prognosis is very poor. We report a case of melanoma in situ localized on the penile shaft. Melanoma in situ of the penis is extremely rare. We emphasize that early diagnosis of melanoma in situ will improve the prognosis of melanoma of the penis.

Atopic retinal detachment. Report of four cases and a review of the literature

Summary Ocular complications of atopic dermatitis include cataract, blepharitis, keratoconjunctivitis, keratoconus, iritis and retinal detachment. The aim of this study was to evaluate the characteristics of retinal detachment in atopic dermatitis patients. We examined four patients with atopic dermatitis and retinal detachment, and performed an extensive review of the literature. There have been about 130 reported cases of retinal detachment in patients with atopic dermatitis from Japan, in comparison with only a few reports from Europe and the U.S.A. An extensive review of the literature revealed that retinal detachment occurs at a young age in atopic dermatitis patients, and that often both eyes are involved. As retinal detachment is not a rare complication of atopic dermatitis, we propose that this type of retinal detachment is designated ‘atopic retinal detachment’. Dermatologists should be aware of this potential complication of atopic dermatitis.

A case of multiple subungual glomus tumors associated with neurofibromatosis type 1.

Glomus tumor is a distinctive neoplasm characterized by the presence of cells that resemble the modified smooth muscle cells of the normal glomus body, which is a specialized form of arteriovenous anastomosis. We report a case of multiple subungual glomus tumors associated with neurofibromatosis and review the literature on the pathophysiology of this association.

Extraction of human Langerhans cells: a method for isolation of epidermis-resident dendritic cells

Langerhans cells (LCs) are immature dendritic cells in the epidermis that play a central role in T-lymphocyte mediated skin immunity. Upon activation with antigenic stimuli, they differentiate drastically into mature dendritic cells while migrating from the epidermis to regional lymph nodes. Thus, in order to study biological details of immature LCs, it is crucial to isolate epidermis-resident, immature LCs without dermal dendritic cell contamination. Methods for extracting LCs from human skin as well as in vitro derivation of LC-like cells from hematopoietic progenitor cells have been described previously, but the cell preparations can potentially contain a significant number of dendritic cells that are not identical to epidermal LCs. Here, we describe a technique by which purely epidermis-resident LCs are extracted from human skin. Following digestion of human skin with dispase, the epidermis was separated mechanically without any attached dermal component. The trypsinized epidermal cells were then fractionated by centrifugation with a discontinuous density gradient composed of bovine albumin and sodium metrizoate. The LC-enriched preparation thus obtained contained 80% to >90% CD1a+, E-cadherin+ cells that expressed Birbeck granules and the Lag protein. Consistent with their being at an immature stage, the freshly isolated LCs lacked the expression of CD83, a marker for mature dendritic cells. The purified LCs were able to activate allogeneic T cells, indicating that the cells retained T-cell stimulation ability even after extraction. Thus, the present work offers an opportunity for precise in vitro studies of epidermal LCs.

An automated method for the quantification of immunostained human Langerhans cells.

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

Focal dermal hypoplasia (Goltz syndrome) associated with multiple giant papillomas

We report a case of focal dermal hypoplasia (FDH) with multiple giant papillomas on nonperimucosal areas. The patient had had cribriform hyperpigmented and depigmented plaques on the trunk and extremities since birth. There were also hypoplastic skin lesions on the right arm, left elbow and right thigh. The multiple giant papillomas began to appear. when she was 22 years old, on the trunk and extremities. Cryotherapy was effective in controlling them.