Distribution of natural killer cells and lymphocyte subclasses in Jessner's lymphocytic infiltration of the skin and in cutaneous lesions of discoid and systemic lupus erythematosus

We studied the cell infiltrates in biopsies from lymphocytic infiltration of the skin (LIS), with six monoclonal T cell antigen-specific antibodies and compared the reactivity pattern with those in biopsies from discoid and systemic lupus erythematosus skin lesions and allergic contact skin reactions. A newly described antibody (NK₉) recognizing natural killer (NK) cells and activated cytotoxic T lymphocytes was included, and the numbers and activity of circulating NK cells was determined. Immunohistochemical staining revealed that the numbers of NK₉-positive cells were highest in LIS. The distribution of T lymphocytes (OKTii + ve), helper T cells (OKT₄+ ve), suppressor T celts (OKT8 + ve), Langerhans cells (OKT6 + ve) and activated T cells (anti-Tac + ve) in LIS differed from those in DLE, SLE and allergic contact reactions. However, the number of circulating NK cells (large granular lymphocytes) and the NK activity in peripheral blood were normal in LIS. We conclude that in LIS a distinct type of T cell activation occurs; the cause of this remains to be determined.     

Epidermal expression of the calcium binding surface antigen 27E10 in inflammatory skin diseases

The expression of the heterodimeric complex of the calcium-binding proteins MRP-8 and MRP-14 was investigated in various inflammatory dermatoses using immunohistochemical staining with the monoclonal antibody 27E10. In addition to the inflammatory infiltrate, a positive staining was repeatedly found in the involved epidermis from patients with lichen planus, lupus erythematosus and psoriasis vulgaris, but not in normal skin epidermis and/or in epidermis from leucocytoclastic vasculitis patients. The keratinocytic expression of the 27E10 antigen was dissimilar to that of the MHC class-II molecules and the adhesion molecule ICAM-1. These data indicate that the 27E10 antigen is a distinct activation marker of inflammatory keratinocytes and may have proinflammatory properties.Presented in part at the 18th annual meeting of the Arbeitsgemeinschaft Dermatologische Forschung (ADF), Mannheim, November 9–11, 1990     

Epidermal keratinocytes express the adhesion molecule intercellular adhesion molecule-1 in inflammatory dermatoses

Using indirect immunofluorescence assays on frozen tissue sections of skin from healthy subjects and subjects with inflammatory skin diseases, we found that intercellular adhesion molecule-1 (ICAM-1) was expressed in a cell surface pattern on epidermal keratinocytes at the site of lymphoid infiltration in cutaneous dermatoses. ICAM-1 was not expressed on epidermal keratinocytes in noninflamed skin. Its expression was not related solely to epidermal hyperproliferation, as hyperproliferative, tape-stripped epidermis did not express ICAM-1. We have reported previously that ICAM-1 expression on epidermal keratinocytes was upregulated by treatment with interferon gamma and that activated T lymphocytes bound to cultured epidermal keratinocytes in vitro by lymphocyte function associated-1 (LFA-1) molecules on T cells and ICAM-1 on epidermal keratinocytes. Taken together, these data suggest that upregulation of expression of ICAM-1 is an important feature of cutaneous inflammation.     

Expression of activated MEK1 in differentiating epidermal cells is sufficient to generate hyperproliferative and inflammatory skin lesions

Epidermal activation of Erk MAPK is observed in human psoriatic lesions and in a mouse model of psoriasis in which beta1 integrins are expressed in the suprabasal epidermal layers. Constitutive activation of the upstream kinase MEK1 causes hyperproliferation and perturbed differentiation of human keratinocytes in culture. It is not known, however, whether Erk activation in differentiating keratinocytes is sufficient to trigger hyperproliferation of basal keratinocytes and a skin inflammatory infiltrate. To investigate this, we expressed constitutively active MEK1 in the suprabasal epidermal layers of transgenic mice. Proliferation in the epidermal basal layer was stimulated and epidermal terminal differentiation was perturbed. Some older mice also developed papillomas. There was a large increase in T lymphocytes, dendritic cells, and neutrophils in the skin. The effects of suprabasal MEK1 on basal keratinocytes and leukocytes, cells that were transgene negative, suggested that MEK1 activity might stimulate cytokine release. Transgenic keratinocytes expressed elevated IL-1alpha and crossing the mice with mice overexpressing the IL-1 receptor in the epidermal basal layer led to exacerbated hyperproliferation and inflammation. These data suggest that activation of MEK1 downstream of beta1 integrins plays an important role in epidermal hyperproliferation and skin inflammation.     

Characterization of the dermal infiltrates in Jessner''s lymphocytic infiltrate of the skin, polymorphous light eruption and cutaneous lupus erythematosus: differential diagnostic and pathogenetic aspects

In the present study a comparative immunohistochemical study was performed on skin biopsies from of patients with Jessner's lymphocytic infiltration of the skin (LIS), polymorphous light eruption (PLE), discoid lupus erythematosus (DLE) and subacute cutaneous lupus erythematosus (SCLE) using a large panel of monoclonal antibodies against T cell differentiation antigens (CD3, CD4, CD8), immunoregulatory T cell subsets (CD7, 4B4, 2H4, Leu 8), B cells (CD22), activated cells CD25, OKT9, HLA-DR), Langerhans cells (CD1) and macrophages (Leu-M5). The results showed many similarities between LIS and PLE. The most important differences between these conditions and CDLE/SCLE were the high proportions of cells reactive with monoclonal antibody Leu-8 and the absence of T cells expressing HLA-DR antigens in LIS and PLE, suggesting absence of local T cell activation in these conditions. The differential diagnostic and pathogenetic aspects of these findings will be discussed.     

Cutaneous T-cell lymphoma lesional epidermal cells activate autologous CD4+ T lymphocytes: involvement of both CD1+OKM5+ and CD1+OKM5- antigen-presenting cells

Cutaneous T-cell lymphoma is characterized by infiltration of the skin by activated CD4+ T lymphocytes. The mechanism by which these T lymphocytes achieve and maintain their activated state is unknown. Antigen-specific activation of T lymphocytes is dependent upon antigen-presenting cells which express HLA-DR class II major histocompatibility complex molecules, such as epidermal Langerhans cells. In addition to CD1+DR+ Langerhans cells, cutaneous T-cell lymphoma lesional epidermis contains major histocompatibility complex class II positive non-Langerhans cell populations, including CD1+OKM5+ bone-marrow-derived cells and DR+ keratinocytes. We asked whether any of these epidermal cell populations demonstrate capacity to activate T lymphocytes. Various numbers of epidermal cells from uninvolved and involved cutaneous T-cell lymphoma plaques were therefore used to stimulate autologous CD4+ and CD8+ T lymphocytes in the absence of exogenous antigen. Involved epidermal cells potently induced proliferation of CD4+ T lymphocytes (S.I. +/- SEM = 466 +/- 45). In contrast, uninvolved epidermal cells only induced background levels of proliferation (S.I. +/- SEM = 2 +/- 0.5, N = 8, p less than 0.01). Neither involved nor uninvolved epidermal cells were able directly to activate CD8+ lymphocytes. The capability of involved epidermal cells to activate CD4+ T lymphocytes was dependent upon CD1+DR+ leukocytes and not DR+ keratinocytes, because depletion of either HLA-DR+, CD1+ or HLe1+ epidermal cells totally abrogated the T-lymphocyte proliferation. Interestingly, on a cell per cell basis CD1+DR+ cells obtained from involved skin, demonstrated relative to CD1+DR+ cells from uninvolved skin, enhanced capacity to activate CD4+ T lymphocytes. Furthermore, CD1+OKM5+ cells from involved epidermis stimulated autologous CD4+ T lymphocytes. This indicates that a unique hitherto undescribed CD1+OKM5+ epidermal antigen-presenting cell population may participate in T-lymphocyte activation. These findings provide support for the concept that the epidermal cells in cutaneous T-cell lymphoma patients, particularly the antigen-presenting cells, may contribute significantly to the activation of CD4+ malignant and/or non-malignant inflammatory T lymphocytes within the skin.     

The circulating lymphocyte profiles in patients with discoid lupus erythematosus and systemic lupus erythematosus suggest a pathogenetic relationship

BACKGROUND: Discoid lupus erythematosus (DLE) and systemic lupus erythematosus (SLE) are chronic inflammatory diseases of unknown aetiology; the relationship of DLE with SLE has been a subject of debate for many years. OBJECTIVES; To find evidence for systemic immune activation in DLE by analysis of the immunophenotypic profiles of circulating lymphocytes, and to compare these changes with those in patients with SLE. METHODS: The immunophenotypic profile of peripheral blood lymphocyte subsets from 23 DLE patients without clinical or laboratory evidence of systemic disease, 25 SLE patients and 38 healthy donors was characterized by two-colour immunofluorescence flow cytometry analysis. None of the patients was receiving corticosteroid or immunosuppressive treatment. RESULTS: Patients with DLE had increased numbers of circulating HLA-DR+ CD3+ T cells and HLA-DR+ CD4+ T cells, indicating systemic T-cell activation, and an expansion of CD5+ CD19+ B cells. Decreased numbers of T-cell subsets expressing the differentiation markers CD11b and CD16/56, and of CD16/56+ natural killer cells were also found. In SLE, the changes were similar but more pronounced. In addition, a profound CD4+ T-cell lymphopenia and an increase of HLA-DR+ CD8+ T cells were found only in SLE. CONCLUSIONS: Our data provide evidence for systemic activation of the cellular immune system in patients with purely cutaneous DLE. Similarities in the lymphocyte immunophenotypic profiles in patients with DLE compared with SLE suggest that there are common immunopathological processes in these two conditions.     

Epidermal keratinocytes of bullous pemphigoid express intercellular adhesion molecule-1 (ICAM-1).

Intercellular adhesion molecule-1 (ICAM-1) is the ligand for lymphocyte function associated antigen-1 (LFA-1), mediating the adhesion of lymphocytes to vascular endothelium. Keratinocytes are known to express ICAM-1 in some inflammatory dermatoses. Using an indirect immunofluorescence method, we examined the patterns of ICAM-1 and LFA-1 staining in bullous pemphigoid (BP) lesions and compared them to pemphigus vulgaris (PV) cases. ICAM-1 was expressed on the cell surface and in the cytoplasm of epidermal keratinocytes at the sites of erythematous and bullous lesions of BP. LFA-1 molecules were expressed on T cells at the basement membrane zone. In addition, HLA-DR-positive keratinocytes were observed in the basal layer. ICAM-1 was not, however, expressed on epidermal keratinocytes in uninvolved skin from BP patients, PV or normal control skin. It is known that ICAM-1 is expressed on keratinocytes at the site of lymphoid infiltration in cutaneous dermatoses and that LFA-1-positive T cells can bind to interferon gamma-induced ICAM-1-positive keratinocytes. Our results suggest that cellular immunity involving ICAM-1 and LFA-1 may play a part in the pathogenesis of bullous pemphigoid.     

Immunohistochemical analysis of chronic discoid and subacute cutaneous lupus erythematosus—relation to immunopathological mechanisms

An immunohistochemical analysis of skin biopsies was performed in 18 patients with cutaneous lupus erythematosus (LE), using the alkaline phosphatase and monoclonal anti-alkaline phosphatase method (APAAP). The study group was subdivided on the basis of clinical criteria into 10 patients with chronic discoid LE (CDLE) and eight patients with subacute cutaneous LE (SCLE). Using a panel of monoclonal antibodies the following results were obtained: (i) ICAM-1 was expressed on epidermal keratinocytes, dermal inflammatory cells, and endothelial cells in most biopsies, whereas LFA-1 was confined to the dermis. Attachments between keratinocytes or endothelial cells and activated T lymphocytes via ICAM-1/LFA-1 may be a possible mechanism of target/effector recognition in cutaneous LE. (ii) HLA-DR was expressed on epidermal keratinocytes and cells of the dermal infiltrate, but not on endothelial cells. HLA-DR⁺ cells probably function as antigen-presenting cells, leading to major histocompatibility complex-restricted cellular cytotoxicity in cutaneous LE. (iii) Interleukin 2 receptor expression on dermal inflammatory cells was weak, indicating non-specific activation of T lymphocytes. (iv) The dermal inflammatory cells were T lymphocytes, mainly of the helper/inducer subtype. B lymphocytes were rarely found in the dermis. In general, no significant immunohistochemical differences were found between CDLE and SCLE, suggesting that these variants represent clinical subtypes rather than different pathogenetic entities.     

银屑病发病机制中T细胞作用的进展

银屑病是一种Th1细胞介导的自身免疫性皮肤病,近来的研究表明,其他细胞也参与其发病过程,尤其是树突细胞、内皮细胞、Th17细胞及调节性T细胞等,其中T细胞的活化、增殖及分化是发病的主要环节,银屑病特征性的角质形成细胞增殖和异常分化及炎性细胞浸润是继发于T细胞活化后释放的细胞因子.一些黏附分子(E/P选择素等)及皮肤淋巴细胞相关抗原-P选择素糖蛋白配体-1复合体和皮肤淋巴细胞相关抗原-CD43复合体在银屑病发病中也起着一定的作用.     

Preliminary evaluation of in vivo reflectance confocal microscopy features of Discoid lupus erythematosus

BACKGROUND: Discoid lupus erythematosus (DLE) can simulate other inflammatory diseases both clinically and histologically. In vivo reflectance confocal microscopy (RCM) is a noninvasive, reproducible imaging technique already reported to be useful in the evaluation of several inflammatory skin conditions such as contact dermatitis, psoriasis and Darier disease. OBJECTIVES: The aims of our study were to define RCM features of DLE and to evaluate its feasibility in biopsy site selection. METHODS: Discoid lesions were selected for RCM evaluation from 10 patients with an established diagnosis of DLE. Subsequently, a 4-mm punch biopsy of the same areas evaluated with RCM was rendered for histopathological examination. RESULTS: A series of RCM features of DLE was identified and shown to correlate well with histopathological evaluation. Interface changes, as well as epidermal, dermal and adnexal inflammatory cell infiltration, were identified with RCM in a high percentage of the lesions. A limitation of RCM examination besides imaging depth was the inability to distinguish lymphocytes from other white blood cells. CONCLUSIONS: The utility of RCM as a diagnostic tool for DLE awaits further evaluation, although it appears to be promising for biopsy site selection.     

Interleukin‐1 from epithelial cells fosters T cell‐dependent skin inflammation

Background Chronic inflammatory skin diseases such as atopic dermatitis and psoriasis are characterized by the infiltration of lymphocytes into the epidermal compartment. Several studies point to an active role of skin epithelial cells in the pathophysiology of such diseases. Objectives In this study we addressed the regulatory function of primary human keratinocytes in the interaction with autologous T cells and monocytes. Methods We used a human coculture model with keratinocytes grown from epidermal stem cells of the outer root sheath of human hair follicles and autologous T cells. Results In our coculture system we observed a high production of interferon (IFN)‐γ, but not Th2 cytokines, in the presence of superantigen or antigen‐pulsed autologous monocytes. Critical parameters for this effect were: (i) T‐cell receptor activation, (ii) an intercellular adhesion molecule‐1/lymphocyte function‐associated antigen (LFA)‐1‐dependent interaction between keratinocytes and T cells, and (iii) secretion of interleukin (IL)‐1β. Remarkably, in the presence of activated T cells, epithelial cells seemed to be a more significant source of IL‐1β than monocytes. Application of the LFA‐1 blocker efalizumab or IL‐1 receptor antagonist anakinra enabled us to suppress completely the production of IFN‐γ by T cells in the coculture. Conclusions IL‐1 secretion and the physical contact between keratinocytes and activated, infiltrating T cells may be central for the development of chronic inflammatory skin conditions.     

Discoid lupus erythematosus with secondary amyloidosis

BACKGROUND: Secondary localized cutaneous amyloidosis is a clinically unapparent phenomenon associated with various cutaneous pathologies, usually tumours of epidermal origin. The amyloid is thought to be derived from keratinocytes. OBJECTIVES: To characterize the amyloid deposition observed incidentally within lesional biopsies from three patients with discoid lupus erythematosus (DLE), and retrospectively to study the phenomenon within DLE skin samples. METHODS: Localized amyloid deposition was observed in three cases of DLE by immunofluorescence studies, and these cases were further studied by histology and immunohistochemistry using a monoclonal anticytokeratin antibody. Retrospective histological review of DLE tissue specimens archived over 12 months was performed to look for evidence of previously undetected amyloid. RESULTS: Amyloid deposition was confirmed histologically in the three index cases by staining with Congo red and thioflavin T. Positive staining with an anticytokeratin antibody demonstrated the epidermal origin of the amyloid protein. Of the 18 archived cases reviewed amyloid was retrospectively detected in one sample. CONCLUSIONS: Secondary cutaneous amyloidosis of keratinocyte origin can be seen in DLE lesions. It may be a not infrequent occurrence and may remain under-reported. We discuss the possible role of disease chronicity and colloid body degradation in the pathogenesis of amyloidosis.     

Is epidermal cell proliferation in psoriatic skin grafts on nude mice driven by T-cell derived cytokines?

Plasminogen activity and DNA synthesis by epidermal cells have been reported to be doubled in psoriatic skin grafts compared with grafts of normal skin 6 weeks after transplantation to nude mice. In our study human lymphocytes disappeared from such grafts within 48 h whilst some DR-positive human dendritic cells were retained in the grafts for up to 4 weeks. However, the grafts were infiltrated by Thy 1.2+ mouse lymphocytes within 6 days and this infiltration persisted at a moderate level throughout the observation period. It consisted of perivascular aggregates, scattered dermal and papillary T cells, and some mouse T cells were also found in the epidermal compartment. Grafts of psoriatic and non-psoriatic control skin were infiltrated to a similar extent, suggesting a low-grade rejection response against the human xenografts. These findings raise the possibility that psoriatic keratinocytes are responding abnormally to inflammatory cytokines released by mouse lymphocytes reacting against the skin grafts.     

Evaluation of lymphocyte activation in skin lesions of patients with mixed connective tissue disease and discoid lupus erythematodes

Summary Biopsy specimens from mixed connective tissue disease (MCTD) and discoid lupus erythematodes (DLE) skin lesions were stained with monoclonal antibodies to differentiation and activation antigens. In addition, the blast cells were studied by combining autoradiography with immunoperoxidase staining. In both disease conditions most of the inflammatory cells in situ were positive for T11 antigen, the CD4/CD8 ratio being low. Only a few of the cells were pan-B positive B cells. The expression of various activation antigens did not differ significantly between MCTD and DLE biopsy specimens; the number of T9, Tac, and 4F2 antigen carrying cells was relatively low, whereas Iapositive cells were more numerous. ³H-Thymidine incorporating T blasts comprised less than 1% of all inflammatory cells. T4 and T8 marker-carrying blast cells were present in about equal proportions. These findings suggest that Ia antigen-expressing T cells are important from the pathogenetic point of view in both MCTD and DLE. Because the local proliferation of T cells was extremely low according to the lack of interleukin-2 receptor and OKT9 markers and ³H-thymidine incorporation, it seems probable that most of the T cells are recruited from the circulation to the site of the inflammation.     

Evaluation of the potential role of cytokines in toxic epidermal necrolysis

Toxic epidermal necrolysis is a rare disease observed as a consequence of adverse reactions to drugs. It results in the widespread apoptosis of epidermal cells and has a high mortality rate. The mechanisms leading to this apoptosis are not yet elucidated. We investigated whether the cytokines present in the blister fluid, which accumulates under necrotic epidermis, originated from T lymphocytes and may play a role in the propagation of keratinocyte apoptosis. Interferon gamma (IFN-gamma), soluble tumor necrosis factor alpha (TNF-alpha), soluble Fas ligand (sFas-L) were present in much higher concentration in the blister fluids of 13 toxic epidermal necrolysis (TEN) patients than in control fluids from burns. The results of RT-PCR studies, however, indicated that only IFN-gamma and to a lesser extent interleukin (IL)-18 were produced by mononuclear cells present in the fluid. That suggests that the other cytokines also present (TNF-alpha, sFas-L, IL-10) rather originated from activated keratinocytes. Fas-L was indeed overexpressed on the membranes of keratinocytes in lesional skin in situ. The Th1 profile of T lymphocyte activation found in the blister fluid of patients with TEN is consistent with a key role for drug-specific cytotoxic T lymphocytes (CTL) as previously reported, the activation of keratinocytes by IFN-gamma making them sensitive to cell-mediated cytolysis. We propose the hypothesis that the production of Fas-L, TNF-alpha, and IL-10 by keratinocytes could be a defense mechanism against CTL rather than a way of propagating apoptosis among epidermal cells.     

Sequence of changes in psoriatic epidermis. Immunocompetent cell redistribution precedes altered expression of keratinocyte differentiation markers

Recent studies suggest that the immune system is involved in the pathogenesis of psoriasis. We studied the expression and distribution of immunocompetent cells and of some chosen differentiation antigens of keratinocytes at various stages of lesion development, using indirect and amplified immunofluorescence, and avidin-biotin-peroxidase method. Serial cryostat sections were collected so as to allow comparative studies of adjacent parts of each biopsy sample with various immunocytochemical markers. Our results indicate that focal intra-epidermal infiltration of otherwise unaltered epidermis with lymphocytes, mostly of the T-helper phenotype, was the first perceptible change occurring in patients with eruptive psoriasis. Modification of the Langerhans' cell staining was observed in these initial subclinical lesions. A significant reduction of the cell frequency was noted in psoriatic papules and plaques. Changes in the epidermal antigen expression could be observed in the developed lesions only. The simultaneous appearance of histologic signs of psoriasis and the modification of keratinocyte antigens indicates that both events are related to the epidermis hyperproliferation, possibly induced by focal inflammatory reaction.     

Immunohistochemical studies on NAP-1/IL-8 in contact eczema and atopic dermatitis

Summary The neutrophil activating peptide NAP-1/IL-8 has in the past been shown to be secreted by diverse cell-types involved in inflammatory processes. Furthermore, potent biological effects on both neutrophilic granulocytes and lymphocytes enforce its role in inflammation. Recently, immunohistochemical studies using monoclonal anti-NAP-1/IL-8 antibodies have been performed on dermal inflammatory conditions like psoriasis vulgaris. These have demonstrated epidermal IL-8 immunoreactivity in a pattern inversely related to the degree of inflammatory infiltration. Based on these results, in the present study biopsies from patients with contact eczema as well as atopic dermatitis were examined. The same patterns of immunoreactivity were found with either homogenous epidermal staining, focally negative staining or overall decreased or even absent staining. As in psoriasis, these patterns were related to the degree of inflammatory infiltration. These results prove NAP-1/IL-8 to be involved not only in psoriasis vulgaris, but more likely to be a marker of different inflammatory processes. Future work will have to examine the kinetics as well as stimuli causing these effect.     

Resident skin cells in psoriasis: a special look at the pathogenetic functions of keratinocytes

Psoriasis is a chronic inflammatory skin disease characterized by exaggerated keratinocyte proliferation. Current paradigm indicates that psoriasis is driven by T cell–mediated immune responses targeting keratinocytes. However, psoriasis cannot be explained solely on the basis of T-cell activation, and it is likely that intrinsic alterations in epidermal keratinocytes play a very relevant role in disease expression. In particular, keratinocytes may be important in initiating, sustaining, and amplifying the inflammatory responses by expressing molecules involved in T-cell recruitment, retention, and activation. Keratinocytes are also a relevant source of growth factors for angiogenesis. Finally, intrinsic defects in cytokine and growth factor signaling in keratinocytes may be responsible for their aberrant hyperproliferation and differentiation to T cell–derived signals. Other skin resident cells such as fibroblasts, mast cells, and endothelial cells also contribute to psoriasis pathogenesis by expressing molecules involved in T-cell recruitment and activation.