In situ identification of Langerhans cells in the dermal infiltrate of cutaneous T cell lymphoma

Current Concepts of the Immunobiology and Immunotherapy of Cutaneous T Cell Lymphoma: Insights Gained through Cross-talk between the Clinic and the Bench

An understanding of the immunologic features of cutaneous T cell lymphoma (CTCL) has led to insights into the life cycle of the malignancy. The identification of the T cell lineage of the neoplastic CTCL cells has allowed unification of diverse clinical presentations under a single entity. The CD4 inducer T cell phenotype of the malignant cells has provided an understanding of the patient's ability to resist infection with certain bacteria. The clonality of the tumor cells, beyond its diagnostic implications, has made them a valuable resource for studying both normal and neoplastic T cell biology. The recently identified immunosuppressive features of the malignant T cells and their dependency for survival on an interaction with immature dendritic cells have explained previously cryptic clinical observations and identified new targets for immunotherapy. Future insights gained both from the bedside and the bench will provide not only an understanding of the immunobiology of the malignancy but also open new avenues for therapeutic intervention.

Cutaneous T-cell lymphoma sparing resolving dermatomal herpes zoster lesions: an unusual phenomenon and implications for pathophysiology

Exclusion of cutaneous T-cell lymphoma (CTCL) by another dermatosis has not been reported. The mechanism for the epidermotropism of helper T lymphocytes in this indolent malignancy is not known. Although there is evidence that Langerhans cells (LC) play a role in the epidermotropism of lymphocytes in CTCL, clinical or in vivo support is lacking. We describe a patient with CTCL who developed herpes zoster involving the left T8 dermatome. When his CTCL became widespread after the herpes zoster healed, the previously affected areas of herpes zoster and their periphery were clinically free of lymphoma. Immunohistochemical analysis of a clinically uninvolved patch revealed absence of CD1a(+) cells in the epidermis, consistent with loss of LC in the areas spared by CTCL. There was no loss of LC in areas affected by CTCL. This is an unusual inhibition of CTCL by a prior viral infection. The loss of LC in the clinically spared skin suggests a role for LC in the epidermotropism of lymphocytes in CTCL.

T lymphocytes bearing the gamma delta T-cell receptor: a study in normal human skin and pathological skin conditions

The aims of this study were to investigate the presence of gamma delta T cells in normal human skin, and the possible role of these cells in cutaneous reactions. Twenty-eight samples of normal skin from various sites, and 52 biopsies from inflammatory and neoplastic skin conditions were investigated by immunohistochemical techniques. In normal human skin gamma delta T cells were infrequently seen in the epidermis and dermis. In the inflammatory and neoplastic dermatoses, gamma delta T cells were occasionally present, accounting for 0-5% of CD3+ cells in most of the biopsies examined. In one case of pityriasis lichenoides chronica and one case of lichen planus gamma delta T cells were found to be increased, accounting for 15% of the CD3+ cells in each case. Dermal gamma delta T cells were markedly increased in three of six cases of Langerhans cell histiocytosis, with up to 30% of dermal CD3+ cells showing positive staining to an anti-T-cell receptor gamma delta monoclonal antibody. In two of these cases gamma delta T cells were seen in both the dermis and the epidermis. In two further cases dermal gamma delta T cells were not a prominent feature, but small clusters of epidermal gamma delta T cells were observed. T cells bearing the gamma delta T-cell receptor are thus not a major feature of normal human epidermis, unlike the murine system, where the great majority of epidermal lymphocytes express the gamma delta T-cell receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of epidermal Langerhans cells in viral infections

Langerhans cells function as highly potent antigen-presenting cells in the epidermis. In the last few years, their role in viral infections has been studied in various experimental systems. They have been shown to be involved in the pathogenesis of a number of infections of viral origin. These include vaccinia virus, human papilloma virus, herpes simplex virus, foot and mouth disease virus and human retrovirus infections. Studies on the effect of various factors, that are known to modulate the activity and density of Langerhans cell in the epidermis, may lead in the future to the development of new strategies aimed at inhibiting virus infections or even eradicating latent infection.

Interdigitating reticulum cells in the dermal infiltrate of mycosis fungoides. An ultrastructural and immunohistochemical study

In order to provide insight into the role of accessory cells in lymphoproliferative neoplasms, 7 cases of mycosis fungoides at various clinical stages--patches, plaques and nodules--were studied ultrastructurally and immunohistochemically. The aim was to establish whether interdigitating reticulum cells are a constant finding in the dermal infiltrate. Their possible relationships with mycosic cells were also investigated. This study revealed that interdigitating reticulum cells were present in all the skin lesions examined, were present in considerable number in the patches and plaques and became sparse in the nodules. Furthermore, in the lesions at various clinical stages these cells showed varying ultrastructural features, probably related to different developmental stages. The close contacts between interdigitating reticulum cells and mycosic cells, the expression of antigenic markers of activation by mycosic cells and the morphological and immunohistochemical signs of progressive de-differentiation of mycosic cells in the more advanced stages suggest that interdigitating reticulum cells are involved in stimulating proliferation and--possibly--neoplastic progression of mycosic cells. A role for the T-cell microenvironment created in the dermis by lymphoid infiltrate in inducing the differentiation of interdigitating reticulum cells from their precursors is proposed.

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.

Electron microscopic and immunolabeling studies of the lesional and normal skin of patients with mycosis fungoides treated by total body electron beam irradiation

Biopsy specimens were taken from lesional and normal skin of nine patients with mycosis fungoides before and after total body electron beam therapy. By electron microscopy, lesional skin had one and one-half to ten times as many epidermal Langerhans cells and indeterminate cells as did the normal skin. In successfully treated lesional skin 1 month after the end of electron beam therapy, the density of epidermal Langerhans cells and indeterminate cells had decreased markedly. In incompletely resolved lesions, Langerhans cells and indeterminate cells were still at pretreatment levels. Epidermal T6 and Ia antigens showed the same pattern of response. Epidermal cell suspensions from lesional and normal skin before and after electron beam therapy were assayed for epidermal thymocyte activating factor. The values of production of this factor did not correlate with the source of the epidermal cells, response to therapy, or the patient's disease course. Skin lesions resembling xerosis and parapsoriasis and histologically lacking the criteria for mycosis fungoides appeared during clinical remissions. These nonspecific skin lesions had densities of epidermal Langerhans cells, indeterminate cells, and T6-positive and Ia-positive cells comparable to levels found in pretreatment lesional skin.

Immunohistochemical study of epidermal Langerhans cells and dermal dendritic cells in benign and malignant skin lesions characterized by a dermal lymphoid infiltrate consisting either of B-cells or T-cells

Skin biopsies from 43 patients with a rather dense dermal lymphoid infiltrate of either inflammatory or neoplastic nature have been investigated. We studied the number, distribution and immunophenotype of epidermal Langerhans cells and dermal dendritic cells. As previously reported, differences in epidermal Langerhans cell and dermal dendritic cell numbers between skin biopsies with a B-cell infiltrate and skin biopsies with a T-cell infiltrate were found, dendritic cells being more numerous in the latter. The main finding of this study was an uneven distribution of epidermal Langerhans cells and dermal dendritic cells in skin biopsies with a T-cell infiltrate: in skin lesions with an inflammatory lymphoid infiltrate, small clusters of epidermal and dermal dendritic cells admixed with T-lymphocytes (predominantly T-helper/inducer cells) and small blood vessels were present at areas of exocytosis. In skin lesions with a neoplastic lymphoid infiltrate larger, more loosely arranged aggregates of dendritic cells and T-cells were seen. These cell aggregations composed of activated (inflammatory or neoplastic) T-cells and dendritic cells may represent the cutaneous homologue of the secondary T-nodule in the lymph node. Both types of cell aggregates may correspond to the dendritic cell-T cell clusters observed in in vitro induced immune responses.

Does radiation-induced abrogation of skin Langerhans cell functions lead to enhanced incidence of skin tumors in patients with genetic disorders of DNA repair?

A hypothesis is presented which states that persons with the genetic disorders xeroderma pigmentosum and ataxia-telangiectasia, manifested by a deficiency of DNA repair, develop cutaneous tumors due to the elimination of reticuloendothelial system cells (Langerhans cells) in the skin, and the subsequent loss of control of epidermal cellular elements.

Dendritic cells in the dermal infiltrate of Sézary syndrome

The dermal infiltrates of four patients with the Sézary syndrome were studied by electron microscopy and the data were evaluated quantitatively. The nuclear contour index of lymphocytes was calculated, and many tumour cells had an index greater than 6.5. Dendritic cells were found in all cases. The dendritic cells contained smooth and rough endoplasmic reticulum, moderately well-developed Golgi apparatus, scanty lysosomes and many thin and intermediate filaments; their surface was scalloped with numerous vesicles. Birbeck granules were not found in the cytoplasm of dendritic cells. Dendritic cells comprised 24% of infiltrating cells and were interspersed with lymphocytes; 75% of the lymphocytes were in contact with dendritic cells; 35% of the lymphocytes in contact with dendritic cells had a nuclear contour index higher than 6.5 and 76% had a nuclear contour index higher than 5. The data strongly suggest a functional relationship between lymphocytes and dendritic cells in the dermal infiltrate of Sézary syndrome. They are discussed in relation to the hypothesis that the disease is a consequence of chronic immune stimulation.

Langerhans cells in verruciform xanthomas: an immunoperoxidase study of 10 oral cases

Ten oral verruciform xanthomas were studied using an immunoperoxidase stain for S-100 protein. All cases exhibited positively stained dendritic cells among the mononuclear inflammatory cell infiltrate at the base of the lesions and to a lesser extent among the "foam cells". The foam cells were, however, negative for S-100 staining. We suggest that, based on these findings, verruciform xanthomas belong to a new category of "non-X histiocytoses" in which the presence of Langerhans cells suggests an immunologic pathogenesis.

Significance of non-lymphoid ('accessory') cells in malignant lymphomas and pseudolymphomas of the skin

We investigated the co-distribution of lymphocyte subpopulations and non-lymphoid 'accessory' cells in 35 cases of cutaneous lymphoproliferative diseases (T-cell lymphoma, 10 cases; B-cell lymphoma, 17 cases; pseudolymphoma, 8 cases) using immunohistochemical methods. T-zone histiocytes and particularly Langerhans cells were abundant in all cutaneous T-cell lymphomas, but were also found in B-cell lymphomas. T-zone histiocytes were associated with T-lymphocytes, especially T-helper cells, but not with T-suppressor cells. Dendritic reticulum cells were essentially confined to well differentiated germinal centres. Macrophages occurred in both lymphomas and pseudolymphomas without definite relationship with either B- or T-cells. In malignant lymphomas of high grade malignancy, macrophages represented the only non-lymphoid cell type. Our results indicate that malignant lymphoid cells, like normal lymphocytes, require definite micro-environments which are, at least in part, maintained by certain non-lymphoid cells.

Clinical and immunohistological characterization of cutaneous lesions in chronic lymphocytic leukaemia

Twenty-five patients with immunologically classified B cell chronic lymphocytic leukaemia (CLL) were examined for skin lesions. Six showed evidence of cutaneous involvement, and histological examination of skin biopsies from these patients revealed perivascular lymphocytic infiltration with some diffuse involvement in three. Immunohistological analysis with a range of B and T cell specific monoclonal antibodies revealed that in all cases the infiltrate was predominantly T cell in origin and that epidermotropism in three cases was also associated with T cell components. Six control patients with macroscopically normal skin were also biopsied and these biopsies subjected to the same assessment. All were normal.

Monoclonal antibodies and cutaneous T cell lymphoma. Theoretical and practical considerations

The T cell nature of mycosis fungoides and Sézary syndrome was established a decade ago. The recent advent of monoclonal antibodies to T cells and other lymphoid subpopulations has resulted in an explosion of knowledge on the biology of this group of disorders. These reagents have increased our knowledge on thymic differentiation status, pathogenesis, the phenotype of premalignant vs malignant lymphocytic infiltrates, the identification of other previously unrecognized cells within lymphomas, and the phenotype of circulating vs skin lymphocytes. Therapeutic applications may result. These new developments are discussed.

In situ study of T-cell subpopulations in cutaneous T-cell lymphoma. Diagnostic criteria

The T-cell subpopulations present in skin biopsy specimens from 91 patients with cutaneous T-cell lymphoma (CTCL) and from 19 patients with benign lymphocytic infiltrates of the skin were examined in situ to define criteria for the differentiation of benign from malignant lymphocytic infiltrates. The monoclonal antibodies OKT 1 (pan T-cell), BE 3 (pan T-cell), OKT 4 (helper/inducer T-cell), OKT 6 (cortical thymocyte and Langerhans' cell), OKT 8 (suppressor T-cell), and OKT 10 (pan thymocyte) were used in direct or indirect immunoperoxidase reactions. Sections were examined at high magnification, and the distribution and percentage of cells reactive with each antibody were assessed. Three main patterns of staining were observed in the CTCL patients: (1) 64% of the biopsy specimens showed that 60% of the cells present in the dermis were T-cells that were OKT 1+ and BE 3+ and there was an even distribution of the different T-cell subpopulations, with 54% being OKT 4+ and 8% OKT 8+; (2) 21% patients showed selective loss of OKT 1 antigen, and 80% of these also showed loss of BE 3 antigen; and (3) 15% patients showed large numbers of OKT 8+ cells (range, 50%-90%) but the percentages of OKT 1+ and OKT 4+ cells were within the ranges seen in Group 1, indicating the presence of a population of T-cells simultaneously expressing OKT 4 (helper/inducer) and OKT 8 (suppressor) reactivity. In 95% of the CTCL patients, 3.5% OKT 6+ cells were present in the dermal infiltrate, and in 92% of patients, 3% OKT 10+ cells were present. Comparing sections from CTCL and benign dermatoses, no single diagnostic feature was identified, but helpful differentiating features were: (1) the even, rather than nodular, distribution of the T-cell subpopulation; (2) the selective loss of OKT 1 and BE 3 antigens; (3) the presence of T-cells simultaneously expressing OKT 4 and OKT 8 antigens; and (4) the presence of OKT 10+ cells.

What's new in dermatopathology?

This review emphasizes the important work in dermatopathology reported in the past 3 years. In reviewing the recent contributions in the field, four areas appear to have received particular attention: (1) new information concerning the histogenesis of cutaneous tumors based on the dual functional capacities of cells; (2) the Langerhans cell and its role in inflammatory and neoplastic processes; (3) prognostic factors in stage I malignant melanoma; and (4) the use of new immunofluorescent and immunohistochemical technics as diagnostic tools in cutaneous pathology.

Antigens specified by the Tla locus are expressed on the surface of murine Langerhans cells

A monoclonal antibody against the murine thymus leukemia antigen TL, was employed to demonstrate the presence of the antigen on the surface of dendritic cells in murine epidermis of Tla-positive strains, B.10A and A.TH. Immunofluorescence and immunoperoxidase staining of EDTA-separated epidermal sheets demonstrated dendritic cells with a distribution pattern and density comparable to that noted for anti-IAk staining. Tla-negative mouse strains such as A.TL, C3H/HeJ, and C57BL/6 did not show any staining of dendritic epidermal cells. Epidermal cell suspensions similarly contained 2-4% cells with discrete surface staining with anti-TL antibody. Capping was noted in these cells. Once again positive results were noted only in appropriate Tla-positive strains. Control staining was carried out in all cases on frozen sections of thymii from mice. Thymocytes in the cortical zones and some dendritic cells at the corticomedullary junction were stained. TL antigen in mouse appears to be analogous to T-6 antigen previously detected on human Langerhans cells.

Kaposi's sarcoma in homosexual men: an immunohistochemical study

A recent outbreak of disseminated Kaposi's sarcoma has been recognized in homosexual men in New York, San Francisco, and Los Angeles. Biopsy specimens of skin lesions were obtained from nine of these homosexual men in Los Angeles and San Francisco. T lymphocyte subset antigens, factor VIII-related antigen, and HLA-Dr antigen were evaluated in situ in frozen sections using immunoperoxidase technics. Factor VIII-related antigen and HLA-Dr antigen were present on tumor cells, supporting a vascular endothelial origin of this neoplasm. Langerhans cells and T lymphocytes were present in numbers similar to that of normal skin in skin specimens from seven patients with Kaposi's sarcoma with visceral dissemination, but were increased in specimens from two patients with only cutaneous involvement.

Mycosis fungoides: an overview

Mycosis fungoides (MF) is a lymphoma that appears to have a unique relationship with the skin. In recent years our knowledge about this disease has increased considerably, in particular regarding the nature of the malignant cells and their functional characteristics. Furthermore, there is mounting evidence suggesting a viral etiology. Since its first description by Alibert in the early part of the past century, MF has been the subject of much controversy in regard to fundamental issues such as clinical and histological criteria for the establishment of the diagnosis [1] as well as its relationship to other lymphomas and skin diseases. Some of this controversy remains today. Mycosis fungoides is a relatively uncommon disease, the incidence being in the order of 1-2 million per year [1,2]. As is the case with most neoplastic diseases, the incidence increases with age; however, relatively speaking MF is not exceptional among individuals in their twenties or thirties. As for sex distribution there is a slight preponderance of men [3-5].

In vitro analysis of lymphocytes: markers and functions

Current dermatologic literature is becoming replete with articles elucidating current concepts in the pathophysiology of lymphocytic diseases. Much of this knowledge emanates from the increasingly sophisticated and complex methods of identifying lymphocytes. No longer does it suffice to know that B lymphocytes or T lymphocytes are present, but rather the key information involves knowing what subsets of these cells are present and/or their functional status. The reader attempting to assimilate all this information is thus confronted with an overwhelming, as well as frequently changing, array of analytic methods. This paper is presented as a review of thinking, principles, and methods employed in research on lymphocytic disease.

A second look at intraepithelial Langerhans cells in mycosis fungoides and related disorders. Ultrastructural study with special reference to Langerhans granules and virus-like particles

Skin biopsies of patients with small and large plaque parapsoriasis, premycotic lesions and mycosis fungoides in different stages were examined. Special attention was paid to the relationships between Langerhans cells (LC) and the neighbouring keratinocytes and lymphocytes. At the contact areas of LC and keratinocytes as well as LC and lymphocytes, particular cell membrane phenomena were observed. Aggregations of Langerhans granules and fusions of granules with LC plasma membranes were found exclusively at LC-keratinocyte interfaces. At LC-lymphocyte contact zones cell membrane appositions were seen. In all cases investigated, virus-like particles were mainly found in LC and indeterminate cells (IDC). In 3 cases lymphocytes also contained these particles. It was of particular interest that virus-like particles were observed in skin specimens of all diseases investigated. Discrimination of these particles from other cellular organelles - especially lysosomes - was difficult, however. The significance of our findings, particularly regarding to the supposed virus aetiology of cutaneous T cell lymphomas, is discussed.

Predominant cutaneous infiltration by OKT6- and OKT8-positive cells in a case of Sézary syndrome

Using an immunoperoxidase (skin biopsy) and an immunofluorescence (peripheral blood, bone marrow punctate) technique, and monoclonal antibodies raised against peripheral mature lymphocytes, T helper subsets, T suppressor subsets, and Langerhans cells, we found a predominant dermal infiltration with lymphocytes of the suppressor phenotype and a predominant epidermal infiltration with Langerhans cells in a patient with Sézary syndrome (cutaneous T-cell lymphoma, CTCL). Repeated peripheral blood examinations showed an increased percentage of lymphocytes of the helper phenotype. A bone marrow examination revealed a ratio of suppressor/helper subsets of 1:4. The findings in the skin seem to be inconsistent with most of the results of previous studies in patients with CTCL; the significance of these findings is discussed.