Heterogeneity of dermal OKT6+ cells in inflammatory and neoplastic skin diseases

Expression of CD1 and HLA-DR by Langerhans cells (LC) in oral lichenoid drug eruptions (LDE) and idiopathic oral lichen planus (LP)

Numbers of Langerhans cells (LC) expressing the common thymocyte antigen (T6/CD1) are similar in oral lichen planus (LP) and in normal oral epithelium; however, expression of class II major histocompatibility antigens (HLA-DR/Ia) by Langerhans cells is greater in lichen planus than in normal epithelium, a phenomenon believed to be associated with activation and antigen presentation. This study quantified the numbers of T6+ve and HLA-DR + ve Langerhans cells in oral lichen planus and lichenoid drug eruptions (LDE) to investigate whether differences may reflect differing routes of antigen presentation. Six patients with oral lichenoid drug eruptions and six control idiopathic oral lichen planus patients had lesional biopsies. An immunoperoxidase technique was used to demonstrate binding of T6 and HLA-DR antibodies to identify dendritic intraepithelial cells as Langerhans cells and activated Langerhans cells, respectively. In lichenoid drug eruptions, the number of HLA-DR + ve LC was significantly lower than the number of T6 + ve LC (P < 0.05), whereas in idiopathic lichen planus the numbers of T6 + ve and HLA-DR + ve LC did not differ significantly (P = 0.20). The results provide evidence for differences in the routes of antigen presentation in lichenoid drug eruptions and idiopathic lichen planus.

Non-Langerhans cell histiocytoses. A new unifying concept

Based on our series of 111 cases of non-Langerhans cell histiocytoses, we present a new unifying concept for this rare group of disorders. The common denominator is the monocyte/ macrophage, which presents with various histologic features probably due to the influence of cytokines. Non-Langerhans cell histiocytoses are classified according to the predominant mononuclear (vacuolated, spindle-shaped, xanthomatized, scalloped, and oncocytic) and/or multinucleate (Touton, ground-glass appearance, Langhans, and foreign body) histiocytic cell types. Variable mixtures of these cell types produce common polymorphous patterns with prominence of vacuolated, spindle-shaped, and xanthomatized histiocytes in juvenile xanthogranulomas and of scalloped and oncocytic histiocytes in adult xanthogranulomas. Rarely, unusual monomorphous reaction patterns are observed: mostly vacuolated histiocytes are seen in the mononuclear variant of xanthogranulomas, (early benign cephalic histiocytosis, and generalized eruptive histiocytoma. Xanthomatized histiocytes predominate papular xanthoma and rarely xanthoma disseminatum, whereas spindle-shaped histiocytes are evident in spindle cell xanthogranuloma and progressive nodular histiocytosis, scalloped histiocytes are evident in most cases of xanthoma disseminatum, and finally oncocytic histiocytes are evident in reticulohistiocytoma and multicentric histiocytosis. Immunohistochemical, ultrastructural, and clinical findings can rationally be adjusted to this unifying concept of non-Langerhans cell histiocytoses. The time course of lesions, the age of the patients, and the presence or absence of underlying internal diseases are, or may, at least partially, be related to and thus explain variations on the theme of the non-Langerhans cell histiocytic reaction.

A subpopulation of Langerhans cells (CD1a+Lag-) increased in the dermis of plaque lesions of mycosis fungoides

The population of CD1a+ cells and the quantity of Birbeck granules were evaluated in comparison with the population of T lymphocytes in a variety of clinical lesions of mycosis fungoides. Anti-CD1a and Lag antibodies that specifically react with Birbeck granules and related structures of human Langerhans cells were used immunohistochemically. CD1a+ cells in the dermis of lesions of mycosis fungoides significantly increased in plaques of the plaque stage and in plaques of the tumor stage. They were most frequent in lesions with CD4+ cells ranging in number from 100 to 150/mm2. These lesions were suspected to be progressing from the plaque to the tumor stage. During the course of the disease, most of the dermal CD1a+ cells had few Lag antigens. These results suggest that dermal CD1a+Lag- cells may promote the progression of mycosis fungoides from the plaque to the tumor stage.

Generalized eruptive histiocytoma: a report of a variant case showing the presence of dermal indeterminate cells

We describe a 14-year-old Japanese girl with a variant of generalized eruptive histiocytoma. She presented with the characteristic features of classical generalized eruptive histiocytoma but with the following minor differences. Clinically, some of the papular eruptions tended to coalesce to form plaques. Histoligically, some of the histiocytic cells were S-100 protein- and OKT-6-positive; these were thought to be indeterminate cells because they lacked Birbeck granules. In addition, PAS-positive cells were few and there were some intermingled lymphocytes and a few eosinophils.

Phenotype, ultrastructure, and function of CD1+DR+ epidermal cells that express CD36 (OKM5) in cutaneous T-cell lymphoma

This study investigated the phenotype and function of different antigen-presenting cells (APC) present within the epidermis of patients with cutaneous T-cell lymphoma (CTCL). Involved epidermis of CTCL compared with uninvolved was found to contain increased numbers of CD1+DR+ APC. This population was heterogeneous and comprised both leucocytes of a novel CD1+DR+CD36 (OKM5)+ phenotype and CD1+DR+CD36- indeterminate/Langerhans cells. The CD1+DR+CD36+ leucocytes did not express TcR-1, CD5, CD15, or CD22, and only a minor population expressed CD11, demonstrating that they were neither T nor B cells, and did not belong to the major CD11+ (OKM1+) blood monocyte population. Electron microscopy of purified CD36+ lesional epidermal cells (EC) demonstrated that they lacked Birbeck granules found on CD1(+)-selected Langerhans cells, and most cells exhibited features of indeterminate cells or macrophages. The capacity of EC from involved epidermis to present alloantigens was found to be increased relative to uninvolved epidermis in all patients tested, and this capacity was critically dependent upon the presence of CD45+DR+ bone marrow-derived cells but not on the presence of CD45-DR+ keratinocytes. Positive selection using MoAb against CD1 and CD36 demonstrated that both cell populations exhibited the capacity to stimulate T cells. The results indicate that a novel antigen-presenting cell population with a unique phenotype is present within involved skin of patients with mycosis fungoides. These cells express CD36 in addition to CD1 and have an ultrastructural appearance consistent with a dendritic antigen-presenting cell derivation.

Lichenoid dermatitis: a clinicopathologic and immunopathologic review of sixty-two cases

We reviewed 62 cases (26 men and 36 women, median age 55 years) of previously diagnosed lichenoid dermatitis and correlated the histologic and immunodermatologic findings with the clinical diagnosis and course. The clinical diagnostic groups were contact dermatitis (6 cases), drug eruption (14), lupus erythematosus (6), lichen planus (3), cutaneous T cell lymphoma (3), chronic dermatitis or neurodermatitis (19), and miscellaneous dermatologic disorders (11). With the use of individual histologic features, a correlation with specific clinical conditions was possible, and the clinical groups of dermatitis, drug eruption, lupus erythematosus or lichen planus, and T cell infiltration could be selected histologically. Direct immunofluorescence studies were of most help in the diagnosis of lupus erythematosus and atypical lichen planus, but these studies should be performed in all cases involving lichenoid inflammation. Although previously the nonspecific term lichenoid dermatitis was used to classify the histologic features in these cases, we found that by careful correlation of histologic, immunodermatologic, and clinical features, we were often able to provide a specific diagnosis.

Ultrastructural changes in epidermal Langerhans cells and melanocytes in response to ultraviolet irradiation, in Australians of Aboriginal and Celtic descent

The effects of exposure to small doses of artificial ultraviolet radiation (UVR) on the ultrastructure of epidermal Langerhans cells (LC) and melanocytes were studied in two groups of Australian subjects, one of Aboriginal and the other of Celtic descent. UV exposure induced an apparent depletion of LC in the epidermis of both groups. However, LC depletion in the Aboriginal subjects was associated with apoptosis, whereas organelle and membrane disruption in the LC of Celtic subjects suggested a reduction by direct cellular damage. LC in Aboriginal epidermis tended to become relocated at more superficial levels following UV exposure, and their Birbeck granules became more numerous. LC in Celtic epidermis appeared to become relocated in a basal location and contained fewer Birbeck granules. The central lamina of the Birbeck granules in Aboriginal LC, which was more electron-dense than that in Celtic subjects prior to UV treatment, was temporarily lost following treatment, while the ultrastructure of Birbeck granules in Celtic LC was unchanged. LC and 'indeterminate cells' in intimate association with lymphocyte-like cells occurred in the basal layer of Celtic epidermis 5 days after exposure. These complexes were not observed in Aboriginal epidermis although isolated lymphocyte-like cells were observed in the same location. Melanocytes in Aboriginal epidermis contained greater numbers of melanosomes than those in Celtic epidermis throughout the experiment. Inactive epidermal melanocytes in Celtic subjects initially responded to UV exposure with a slight increase in melanosome content followed by a substantial further increase, whereas active melanocytes in the Aboriginal subjects showed the opposite response. The implications of the different responses of LC and melanocytes in the two groups, in relation to immunological function of the epidermis and the marked racial difference in the incidence of skin cancer, are discussed. Cancer of the skin, particularly basal and squamous cell carcinoma, occurs primarily in people with fair skin who burn easily following exposure to ultraviolet radiation (UVR). In contrast, the incidence of skin cancer in inherently dark-skinned people is low. Melanin is synthesized by melanocytes in response to UVR and is thought to protect epidermal cells against damage to their genetic material by absorbing UVR and thereby reducing its penetration into the skin. Thus darkly pigmented skin is more resistant to the effects of UVR.(ABSTRACT TRUNCATED AT 400 WORDS)

Congenital self-healing histiocytosis (Hashimoto-Pritzker). An ultrastructural and immunohistochemical study

Congenital self-healing histiocytosis (CSHH) is a rare primary histiocytic skin disorder. Only a few cases have been studied by ultrastructure and immunohistochemistry. Here we report a new case that was investigated using an electron microscope and a panel of monoclonal (MCA) and polyclonal (PCA) antibodies. CSHH cells were found to bear the immunohistochemical phenotype of normal epidermal Langerhans cells (LC) and histiocytosis X (HX) cells (CD1a/c+, CD1b-, CD4+/-, human leukocyte antigen [HLA]-DR/DQ+, S-100+). However, an electron microscope showed a paucity of Birbeck granule (BG)-containing cells. This contrasted with their immunophenotype. This finding, along with other ultrastructural characteristics of CSHH cells, suggests that histologic differences exist between CSHH and HX. However, because no absolute histologic criterion is known that allows unequivocally the differential diagnosis between the two diseases, this distinction currently has to rely on clinical criteria, mainly the regressive course observed within a few months in CSHH. The precise nosologic position of CSHH among other histiocytic syndromes remains unsettled.

Clinical implications of immunologic phenotyping in cutaneous T cell lymphoma

The composition of cutaneous lesions from 158 patients with confirmed cutaneous T cell lymphoma, 91 patients with suspected cutaneous T cell lymphoma, and 145 patients with lymphoid disorders other than cutaneous T cell lymphoma was quantitated in situ with the use of commercially available murine monoclonal antibodies that identify the Pan T, T-helper/inducer (Th), T cytotoxic/suppressor (Ts), and Pan B lymphocyte subsets. On average, cutaneous infiltrates of confirmed cutaneous T cell lymphoma were found to contain significantly more Th and less Ts or Pan B cells compared to benign lymphoid disorders. Moreover, when analyzed in terms of the type of lesion examined by biopsy, the absolute amount of Th cells progressively expands with increasing magnitudes of infiltrate in the dermis while the amount of Ts and Pan B cells remains relatively constant among lesions. A useful diagnostic criterion (anti-Leu 1/4 greater than or equal to 70% and anti-Leu 3a/anti-Leu 2a ratio greater than or equal to 6) correctly discriminated between cutaneous T cell lymphoma and non-cutaneous T cell lymphoma in 87.5% of cases. A positive immunodiagnostic result also may be useful for the prediction of subsequent histopathologic confirmation of cutaneous T cell lymphoma in patients who have suspect lymphoid infiltrates, such as alopecia mucinosis or idiopathic generalized erythroderma, when first seen. With the use of multivariate analysis, stage and possibly the percentage of Th cells within the T cell component in cutaneous infiltrates were covariates with significant relationships to survival in patients with confirmed cutaneous T cell lymphoma. In addition, Ts cells in infiltrates did not correlate significantly with observed responses to topical treatment and subsequent course in pretumorous mycosis fungoides. These results indicate that Ts cells play little biologic role in modifying the natural history of cutaneous T cell lymphoma.

Immunogold labelling of epidermal Langerhans cells on tissue sections of normal human skin

A colloidal gold staining procedure was developed for immuno-electron microscopy, which allowed the demonstration of T6 surface antigens of epidermal Langerhans cells on sections of normal human skin with consistent ultrastructural preservation of subcellular structures. All the observed Birbeck granule-bearing Langerhans cells revealed immunogold labelling along the plasma membrane. The penetration of the tissue by the gold particles was adequate, as was the sensitivity and the specificity of the reaction. A major advantage of the present method in comparison with immunoperoxidase techniques is the absence of non-specific staining of the membranes of keratinocytes facing the labelled plasma membrane of the Langerhans cells.

Eczematous reactions in atopic patients caused by epicutaneous testing with inhalant allergens

To determine whether inhalant allergens could induce eczematous lesions we studied 17 patients with atopic eczema (with or without allergic rhinitis), 13 patients with allergic rhinitis without atopic eczema and 10 healthy control subjects. The allergens, birch pollen (Betula verrucosa) and house dust mite (Dermatophagoides pteronyssinus), were applied in aluminium chambers for 48 h on clinically normal skin. In 17 patients with atopic eczema, six epicutaneous test reactions of the delayed type to birch pollen and three to house dust mite were seen at 48 or 72 h. In 13 patients with allergic rhinitis without eczema there was one delayed reaction to birch pollen and none to house dust mite. No delayed type test reactions to either allergen were seen in the controls. Biopsies of the positive test sites revealed an eczematous reaction with epidermal spongiosis and microvesiculation. Immunostaining of cryostat sections showed dermal cell infiltrates consisting of mainly T lymphocytes (ratio of T4:T8, 2-6:I) and to a lesser degree Langerhans and indeterminate T6+ cells. 50-90% of the cells were Ia+. The numbers of basophils and mast cells did not exceed 10-15%.