Seiichiro Sagami

Dermal Nerve Sheath Myxoma

A case of dermal nerve sheath myxoma on the left palm of 26‐year‐old Japanese man is presented. We examined this tumor by light and electron microscopies. On light microscopic examination, this tumor was characterized by a multilobulated myxoid tumor composed of stellate cells in an abundant mucous matrix. This histological feature resembled previously reported cases of dermal nerve sheath myxoma. On electron microscopic examination, the findings of these tumor cells were similar to those of the perineurial cells. These microscopical examinations have provided evidence for an origin from perineurial cells rather than Schwann cells.

Effects of protein kinase C activators on mouse skin in vivo

Tumor-promoting phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA) is known to have many biological effects on epidermal cells [14]. TPA activates protein kinase C directly both in vivo and in vitro [3], and protein kinase C is the receptor of TPA [5, 8]. Therefore, it is possible that biological effects of TPA on epidermis are mediated by protein kinase C, which is also known to be activated by diacylglycerol generated from phosphoinositides of cell membrane [9]. It has been reported that synthetic diacylglycerol, 1-oleoyl-2-acetylglycerol (OAG), as well as TPA, is able to penetrate cell membrane and activate protein kinase C in intact cells [1, 4, 9]. OAG has some biological effects on epidermal cells as does TPA [7, 12]. We investigated marcoand microscopic changes that could be induced by topical application of OAG, as compared with application of TPA. Dorsal skin (6 cm z) of Balb/c and Swiss-Webster mice aged 10 weeks were shaved with an electric shaver so as to avoid injury. TPA (20 gg) and OAG (40 rag) were each dissolved in 100 ~tl acetone. Each 100-1~1 acetone solution was applied with a microsyringe onto the shaved back skin of the mice. In consideration of previous reports [7, 11] these concentrations of TPA and OAG could be thought to be effective biologically on epidermal cells; 100 lal of acetone only was used as control. Five mice were used per group. The mice were treated with each solution once weekly for 3 weeks. They were killed 1 week after the last treatment, and the skins were taken and stained with HE. The hair regrowth patterns in each group of Balb/c mice are shown in Fig. 1 a c . Hair regrowth

Immunohistological identification of protein kinase C isozymes in normal and psoriatic epidermis.

Protein kinase C (PKC), the Ca 2 + and phospholipiddependent protein kinase, is activated by diacylglycerol, which is generated from inositol phospholipids of plasma membrane, and it is recognized that PKC functions as a transducer in the transmembrane signal transduction system [7]. PKC is also known to be activated by tumor promoter, 12-O-tetradecanoyl phorbol-13-acetate (TPA), and it is a receptor protein of TPA [7]. Since it is well known that TPA has striking effects on epidermal proliferation and differentiation, it is possible that PKC has an important role in the regulation of epidermal function [5, 8]. It has been reported that PKC is present in human epidermis [1] and that its activity is lower in psoriatic epidermis than in epidermis from a normal healthy person [3]. Therefore, abnormal proliferation and differentiation of psoriatic epidermis may be relevant to alterations in PKC-mediated processes due to decreased PKC activity. Recently, at least three different isozymes types I (7), II (/~), and III (c 0 of PKC have been identified biochemically [6]. In the present study, localization of PKC isozymes was examined in normal epidermis from a healthy person as well as in both involved and uninvolved epidermis from a psoriatic person using immunohistological study. Skin biopsy specimens were obtained from trunks of three healthy and three psoriatic persons aged 4 0 6 0 years old. The biopsy specimens were immediately snap-frozen in liquid nitrogen, and stored at 7 0 ~ until used. Serial 5-gin

Electron microscopic study on Langerhans cells and related cells in lymph nodes of DNCB-sensitive mice.

SummaryTo understand contact hypersensitivity, it is important to know the kinetics of Langerhans cells (LC) and related cells in the lymph node (LN), as well as in the skin. For this purpose, we tried experimentally to induce increased numbers of LCs, Birbeck granule-like structure (BgS)-containing cells, and interdigitating reticulum cells (IDC) in DNCB-sensitive mice and studied them by means of electron microscopy with the following results: (1) cytologically, LC, BgS-containing cells and IDC were closely related; (2) BgS seemed to arise from rough-surfaced endoplasmic reticulum (r-ER), and BgS-containing cells were midway in nature between LC and IDC from the morphological view point. From these findings, it appears that IDC, BgS-containing cells, and LCs were simultaneously involved in the contact hypersensitivity reactions of LNs.

Actin filament and desmosome formation in cultured human keratinocytes

Cytoskeletal systems have an essential role in the maintenance of cell shape. It has also been reported that they have important roles in various cell functions, such as growth, differentiation, and cell to cell contact. The presence of actin in keratinocytes has been confirmed in previous reports [4, 5], as has the presence of other cytoskeletal proteins (keratin and tubulin). The culture of keratinocytes at a reduced concentration of Ca 2 + prevents desmosome formation. Raising the concentration of Ca 2 + in the medium induces desmosome formation [2]. Recently it was reported that actin filaments developed sooner than desmoplakin (one of the desmosomal proteins) and keratin filaments developed along the cell membrane of mouse keratinocytes after the addition of Ca 2+ into the low Ca 2+ medium [1]. These findings indicate that actin filaments may play a crucial role in desmosome formation in cultured mouse keratinocytes. Using phase-contrast, immunofluorescence, and electron microscopic studies, we investigated whether cytochalasin B (CB), which induces the disruption of actin filaments, affected Ca 2 +-induced desmosome formation in cultured human keratinocytes. Human keratinocytes were obtained from foreskin and subcultured in serum-free modified MCDB 153 supplemented with epidermal growth factor (10 ng/ml), insulin (5 gg/ml), hydrocortisone (0.5 gg/ml), and bovine pituitary extracts (150 tag/ml). The calcium concentration was 0.15 raM. The distribution of actin filaments and desmoplakin was examined in keratinocytes cultured in low Ca 2 + medium and after 24 h culture following the addition of 1.2 mM Ca 2 +. In order to observe the effects of CB on CaZ+-induced desmosome formation, cells grown in low Ca 2 + medium were exposed to CB for 2 h before the addition of Ca 2 +. CB was dissolved in DMSO

Cutaneous Eruptions Induced by Granulocyte Colony‐stimulating Factor in Two Cases of Acute Myelogenous Leukemia

Recombinant human granulocyte colony‐stimulating factor (rhG‐CSF) induced cutaneous eruptions in two cases of acute myelogenous leukemia. In both cases, the eruptions appeared during rhG‐CSF therapy for neutropenia induced by the remission‐induction chemotherapy and disappeared rapidly after the discontinuance of rhG‐CSF therapy. Histopathology of those eruptions revealed dermal cell infiltrations consisting of some neutrophils and atypical cells. It was interesting that, although there were no leukemic cells in the peripheral blood or bone marrow, eruptions containing many leukemic cells appeared. The mechanism of the appearance of these eruptions was unclear, but it was considered that a few leukemic cells might have responded to rhG‐CSF and proliferated in the skin.

Interleukin‐2 Production of T Cells in Atopic Dermatitis

Patients with atopic dermatitis (AD) were treated with Tranilast. Interleukin‐2 (IL‐2) (production of T cells in vitro) and blood histamine values, before and after Tranilast therapy, were measured, and the following results were obtained: 1) Compared with healthy controls, the IL‐2 producing ability of T cells in patients with AD was increased. 2) After Tranilast therapy, IL‐2 production of T cells in AD decreased in quantity to the control level. 3) Skin lesion severities of AD were correlated with the quantity of IL‐2 production of T cells. 4) Serum histamine levels were not significantly different between AD patients and healthy controls, before or after Tranilast therapy.

Reactivity and Persistence of Local Immunological Memory on Murine Contact Hypersensitivity

In a rechallenge system examining murine contact hypersensitivity to DNFB in BALB/c mice, the reactivity to the specific antigen at the previously responded site and the persistence of an immunological memory were investigated. Flare‐up reactions were induced 4 weeks after the first challenge only at the previously responded site by local or systemic administrations of minute quantities of a specific antigen. The intensity of ear swelling was dependent on the quantity of applied antigen at the time of the rechallenge. The local hypersensitivity to the specific antigen observed in the previously responded site and the regional lymph node persisted for at least 1 year.

Increased Langerhans cells and related cells in mesenteric lymph nodes of DNCB-sensitive mice.

SummaryWe used electron microsopy to study mesenteric lymph nodes (LNs) of 2,4-dinitro-1-chlorobenzene (DNCB)-sensitive mice. It was found that Langerhans cells (LCs) and cells containing Birbeckgranule-like structures (BgSs) increased in number only after challenge with DNCB. This increase reached a peak 4 h after challenge. LCs and BgS cells were only found in the paracortical area of LNs. There were no appreciable differences in the morphology of LCs, BgS cells, and interdigitating reticulum cells (IDCs), except for the presence or absence of Bgs or BgSs. No LCs, BgS cells, or IDCs were found in the marginal sinus of mesenteric LNs or in the surroundings of afferent blood vessels. These findings were in complete agreement with those obtained in our previous study of cutaneous LNs. From our findings and the results of previously published studies, we propose the following conclusions: first, LCs and BgS cells observed in mesenteric LNs are the product of the differentiation and maturation of precursor cells pre-existing in the paracortical area of LNs caused by DNCB stimulation. Second, the activated T lymphocyte to DNCB pre-exists in the paracortical area; thus, the DNCB used for challenge stimulates this T lymphocyte to release lymphokine, which then causes some precursor cells to differentiation into LCs and/or BgS cells. Finally, morphological findings suggest that precursor cells of LCs and BgS cells are probably IDCs.

Flow Cytometric Analysis of Protein Kinase C in Lymph Node Cells during the Induction Phase of Contact Hypersensitivity Reaction

On the fourth day after a single painting of 2,4,6‐trinitro‐chlorobenzene on the abdominal skin, inguinal lymph nodes were removed, and a single‐cell suspension was prepared. The cells were analyzed flow cytometrically, using monoclonal anti‐protein kinase C antibody. It was found that the number of lymph node cells in which protein kinase C was detected on the cell surface was significantly increased over that in non‐treated mice (p<0.01). On the basis of our results and discussions in the literature, it is thought that protein kinase C is related to the initiation of the contact hypersensitivity reaction.