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

Study of the reactive dendritic cells in small B-cell lymphoproliferations of the skin

Distinguishing between low-grade primary cutaneous B-cell lymphoma (LG-pCBCL) and cutaneous lymphoid hyperplasia (CLH) based on histological features is often difficult. CLH lesions contain numerous reactive cells of the histiocyte lineage [Langerhans cells (LC), dermal dendritic cells (DDC), and macrophages], which are also often present in CBCL. The aim of this study was to determine whether immunohistochemical detection of those cells could help differentiate between CLH and LG-pCBCL. We determined the percentages of those histiocytic cells in the dermal infiltrates of 45 cases of cutaneous lymphoproliferations comprising 16 CLH and 29 LG-pCBCL (19 follicle-center cell lymphomas and 10 marginal zone lymphomas) by immunohistochemical labeling with antibodies to CD1a, FXIIIa, and CD68 to respectively detect LC, DDC, and macrophages. To avoid observer-dependent bias, an automated morphometric analysis method was used to recognize immunoreactive cells and calculate their percentages within the infiltrate. FXIIIa(+) cells were significatively more frequent in CLH than in LG-pCBCL, whereas CD1a(+) and CD68(+) cell frequencies were comparable in the two groups. The results of our study suggest that DDC might play an important role in the genesis of cutaneous lymphomas.

Langerhans cells and lymphocyte subsets in human gastrointestinal carcinomas. An immunohistological study on frozen sections

In an immunohistochemical study of 38 human gastric and 40 human colonic carcinomas Langerhans cells, suppressor and helper lymphocytes were identified on frozen sections by using anti-CD1, anti-CD8 and anti-CD4 monoclonal antibodies. Tumours were divided into those with few (< 3 per high power field) and those with many (> 3 per high power field) Langerhans cells as well as into those with high number of CD4 and CD8 cells (> 30 per high power field). No significant difference in the number of Langerhans cells regarding histologic types, degree of differentiation and metastatic/non-metastatic groups of either gastric or colonic carcinomas was found. On the contrary the numbers of Langerhans cells related significantly (p < 0.05) to density of T-cell and especially CD4 cell infiltrations of gastric and colonic carcinomas. This finding supports the role of Langerhans cells as antigen presenting cells and their involvement in T-cell activation against neoplastic cells of human gastrointestinal carcinomas.

Papular acrodermatitis of childhood (Gianotti-Crosti disease)

An 11-year-old boy had lentil-sized lichenoid papules, localized to the limbs and trunk, together with acute, nonicteric, hepatitis B surface antigen-positive hepatitis. The clinical picture and course were typical of Gianotti-Crosti disease. Monoclonal antibodies were used to study the lymphocyte subpopulations and surface antigens in the inflammatory infiltrate in frozen sections of a skin biopsy specimen. The results provide data on the pathogenic mechanism of the papular exanthem.

Langerhans cells and mycosis fungoides--a critical overview of their pathogenic role in the disease

Skin biopsies from seven patients with mycosis fungoides in various clinical stages (patches, plaques, nodules) were studied immunohistochemically and ultrastructurally, with the aim of investigating and quantifying the distribution of Langerhans cells and their relationships to mycosis cells. Our findings have revealed that in patches and plaques both Langerhans cells and mycosis cells were numerous in the epidermis. Notwithstanding this, in all the specimens examined, only one Langerhans cell forming close contact with a mycosis cell was detected. In the nodules, Langerhans cells and mycosis cells were sparse in the epidermis and no contacts were seen between them. Moreover, in all the patients studied, only a single Langerhans cell was found in the dermal infiltrate without any closely related mycosis cells. Conversely, numerous interdigitating cells have been found in the dermis of patches and plaques, often tightly adhering to mycosis cells. In the nodule, a few scattered interdigitating cells were seen, but often these had close contacts with neoplastic lymphoid cells. These findings indicate that close apposition between Langerhans cells and mycosis cells, which led previous authors to hypothesize a persistent stimulatory action of Langerhans cells on T lymphocytes, eventually leading to the malignant transformation of the latter, is unusual in mycosis fungoides. Therefore, if such a pathogenic role may be attributed to accessory cells in mycosis fungoides it is more probably exerted by dermal interdigitating cells and not by Langerhans cells, as previously proposed.

S-100 protein-positive dendritic cells in colorectal adenocarcinomas. Distribution and relation to the clinical prognosis

Dendritic cells (DC) in 121 colorectal adenocarcinomas were investigated immunohistochemically, using anti-S-100 protein antibody. S-100(+)DC were recognized among the malignant cells and/or around the tumor and differed in distribution either from lysozyme-positive macrophages or from neuron-specific enolase-positive neural tissue. Patients with many S-100(+)DC (more than 30 cells per 10 high-power fields) in the tumor survived longer than did those with few such cells (less than 30 cells), most often with no metastases (P less than 0.001). The grade of S-100(+)DC infiltration was related to both density of lymphocytic infiltration in the primary tumor and the degree of paracortical hyperplasia in the regional lymph nodes (P less than 0.05). Dendritic cells, therefore, as antigen-presenting cells, conceivably mediate cell immunity in a tumor with lymphoid infiltration and in the regional lymph nodes. The number of S-100(+) DC in the primary colorectal carcinomas represents one aspect of such a series of antitumor immunoreaction, in vivo.

S-100 protein-positive dendritic cells in colorectal adenocarcinomas. Distribution and relation to the clinical prognosis

Dendritic cells (DC) in 121 colorectal adenocarcinomas were investigated immunohistochemically, using anti-S-100 protein antibody. S-100(+)DC were recognized among the malignant cells and/or around the tumor and differed in distribution either from lysozyme-positive macrophages or from neuron-specific enolase-positive neural tissue. Patients with many S-100(+)DC (more than 30 cells per 10 high-power fields) in the tumor survived longer than did those with few such cells (less than 30 cells), most often with no metastases (P less than 0.001). The grade of S-100(+)DC infiltration was related to both density of lymphocytic infiltration in the primary tumor and the degree of paracortical hyperplasia in the regional lymph nodes (P less than 0.05). Dendritic cells, therefore, as antigen-presenting cells, conceivably mediate cell immunity in a tumor with lymphoid infiltration and in the regional lymph nodes. The number of S-100(+) DC in the primary colorectal carcinomas represents one aspect of such a series of antitumor immunoreaction, in vivo.

Plasmacytoid T cells in a case of lymphocytic infiltration of skin. A component of the skin-associated lymphoid tissue?

A case of cutaneous lymphocytic infiltration with large numbers of plasmacytoid T cells (PTC) is reported. Lectin staining and immunohistological analysis revealed that PTC and cutaneous dendritic cells showed a similar expression of concanavalin A, LN2, and MT1. Moreover, differences in TAL 1B5 and S-100 expression were noted. From these findings we suggest that PTC may occur in the skin as a component of the skin-associated lymphoid tissue.

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.