Neoplastic Langerhans Cells Research Articles

FOXP3, CD208, and CD206 Expression in Canine Cutaneous Histiocytoma.

Canine cutaneous histiocytoma (CCH) is a noninfectious tumor that spontaneously regresses. It is suggested that this regression is due to tumor cell maturation, which is responsible for CD8 lymphocyte activation and tumor cell destruction. Nevertheless, the possible role of the immune microenvironment in tumor regression has not been investigated to date. The aim of this study was to investigate the expression of CD208 and FoxP3 as markers of dendritic cells and regulatory T lymphocytes, respectively, and tumor cell expression of CD206 as a marker of Langerhans cell activation, and relate these parameters to the different phases of CCH and to intratumoral T cell infiltration. Formalin-fixed, paraffin-embedded samples from 31 CCH were evaluated. In each case, the mitotic count and regression phase were recorded. Within the tumor, a quantitative evaluation of immunolabeled CD208+ cells, FoxP3+ cells, and CD3+ lymphocytes was performed, as well as the CD206+ tumor cell location. Intratumoral CD208+ cells correlated with CD3+ lymphocytic infiltration. The possible role of dendritic cells in tumor regression was not confirmed since CD208 seemed to be a nonspecific marker for canine dendritic cells. FoxP3+ lymphocyte density was not correlated with any parameter. Neoplastic Langerhans cells presented progressive CD206 expression, from the bottom of the tumor to the epidermis, which correlated with the tumor regression phase and with intratumoral T lymphocyte infiltration. In conclusion, we confirmed a CD206 phenotype change in tumor cells in a spatial group-related pattern, supporting the hypothesis that tumoral Langerhans cells acquire a mature phenotype with tumor regression.

CyclinD1 Is Useful to Differentiate Langerhans Cell Histiocytosis From Reactive Langerhans Cells.

Langerhans cell histiocytosis (LCH) is a rare histiocytic disorder characterized by clonal proliferation of neoplastic Langerhans cells (LCs). LC proliferation can also be seen in different reactive dermatosis. CyclinD1 is a downstream marker of mitogen-activated protein (MAP) kinase pathway, which is often activated in LCH. This study aimed to evaluate the role of cyclinD1 to differentiate reactive LC proliferation from LCH. All cases of cutaneous LCH diagnosed by biopsy in the past 3 years (n = 13) were immunostained with CD1a, p53, CD31, and cyclinD1. Seven cases each of discoid lupus erythematosus (DLE) and lichen planus (LP) were taken as control. Presence of p53, CD31, and cyclinD1-positive LCs (CD1a-positive) were compared in the dermis. In all LCH cases, dermal neoplastic LCs showed diffuse CD1a positivity and 12 cases (92.3%) showed variable (30%-70%) cyclinD1 expression. Weak p53 and CD31 expression were seen in 61.5% and 46.1% of LCH cases, respectively. In the control group, 5 cases of LP and 4 cases of DLE showed variable LC proliferation, highlighted by CD1a positivity. However, no case of reactive dermatosis showed cyclinD1 or p53 expression by the reactive LCs. Weak and patchy CD31 expression by the reactive LCs were found in 1 (25%) and 2 (40%) cases of DLE and LP, respectively. To conclude, cyclinD1 is frequently expressed in neoplastic LCs in LCH. It is an efficient marker to differentiate neoplastic from reactive LC proliferation, and can be used as a surrogate marker in LCH.

Frequency of MAP2K1, TP53, and U2AF1 Mutations in BRAF-mutated Langerhans Cell Histiocytosis: Further Characterizing the Genomic Landscape of LCH.

Langerhans cell histiocytosis is a proliferative disorder of neoplastic Langerhans cells with activating mutations in the Erk signaling pathway. TP53 and U2AF1 mutations have been implicated in other myelomonocytic malignancies and we hypothesized that mutations in these genes may cosegregate in LCH patients according to BRAF mutation status. Towards this end, we collected cases with a pathologic diagnosis of Langerhans cell histiocytosis from Stanford University Hospital. We analyzed the status of known pathogenic alleles in BRAF, ARAF, TP53, U2AF1, and MAP2K1 on formalin-fixed, paraffin-embedded tissue by direct sequencing. A total of 41 cases (71%) had a BRAFV600E allele detected by sequencing. MAP2K1 mutations were also detected in 5 cases: 3 of 17 (18%) cases with wild-type BRAF and 2 of 41 (5%) cases with BRAFV600E mutations (P=0.14). No cases contained the previously reported ARAF mutation, Q347_A348del. All 10 cases with TP53 mutations contained mutant BRAFV600E allele (P=0.021). Of the 11 cases with U2AF1 mutated, 9 of 41 cases co-occurred with BRAFV600E mutations (P=0.31) and 2 of 17 with wild-type BRAF. Interestingly, we do not find that somatic activating MAP2K1 mutations are mutually exclusive with BRAFV600E mutations as has been reported previously. Instead, our data suggests that MAP2K1 mutations may be present along with BRAF either at diagnosis or may be acquired during disease progression. Furthermore, we demonstrated that likely deleterious TP53 mutations correlate with BRAF mutational status and may play a role in the underlying pathogenesis.

Macrophages in Langerhans cell histiocytosis are differentiated toward M2 phenotype: Their possible involvement in pathological processes

Although numerous macrophages are found in the lesions of Langerhans cell histiocytosis (LCH), their activation phenotypes and their roles in the disease process have not been clarified. Paraffin-embedded LCH samples were examined on immunohistochemistry and it was found that CD163 can be used to distinguish infiltrated macrophages from neoplastic Langerhans cells (LC). The number of CD163-positve macrophages was positively correlated with the number of multinucleated giant cells (MGC), indicating that most MGC are derived from infiltrated macrophages. A significant number of CD163-positive macrophages were positive for interleukin (IL)-10 and phospho-signal transducer and activator of transcription-3 (pSTAT3), an IL-10-induced signal transduction molecule. This indicates that these macrophages are polarized to anti-inflammatory macrophages of M2 phenotype. Tumor-derived macrophage-colony-stimulating factor (M-CSF) was considered to responsible for inducing M2 differentiation of infiltrated macrophages. The number of CD163-positive macrophages in different cases of LCH varied, and interestingly the density of CD163-positive macrophages was inversely correlated with the Ki-67-positivity of LC. Although the underlying mechanism is not fully elucidated, macrophage-derived IL-10 was considered to be involved in the suppression of tumor cell proliferation via activation of STAT3.

E-cadherin expression in canine cutaneous histiocytomas

Canine cutaneous histiocytoma is a common skin tumour of Langerhans cell origin. Langerhans cells are members of the dendritic cell family of antigen-presenting cells and are located in the epidermis....

CCH cells are potent stimulators in the allogeneic mixed leucocyte reaction

Canine cutaneous histiocytoma (CCH) has been identified as a tumour of epidermal Langerhans cells (LCs) on the basis of immunophenotypic studies. Neoplastic Langerhans cells (CCH-LCs) were isolated from lesions of canine cutaneous histiocytoma. The CCH-LC cells expressed CD1b, CD11/18, CD45, MHC-I, and MHC-II. The CCH-LC cells were potent stimulators of the mixed leucocyte reaction (MLR) in vitro when compared to PBMCs from the tumour-bearing animals. This provides evidence that the neoplastic cells in CCH have functional as well as immunophenotypic characteristics of Langerhans cells.

The vesicular monoamine transporter 2 (VMAT2) is expressed by normal and tumor cutaneous mast cells and Langerhans cells of the skin but is absent from Langerhans cell histiocytosis.

Monoamine storage in secretory granules is mediated by the vesicular monoamine transporters 1 and 2 (VMAT1 and VMAT2). The aim of our study was to identify monoamine-handling normal and neoplastic inflammatory cells in the skin by their expression of VMAT1 and VMAT2. Normal skin from various parts of the body, as well as 21 cases of cutaneous mastocytosis and 10 cases of cutaneous Langerhans cell histiocytosis were analyzed by immunohistochemistry, radioactive in situ hybridization, and double-fluorescence confocal microscopy. VMAT2-positive cells in the subepidermal layer were identified as mast cells by their expression of tryptase. Neoplastic mast cells in all cases of cutaneous mastocytosis retained their VMAT2 positivity. The intraepidermal VMAT2-expressing cells were identified as Langerhans cells by their CD1a positivity. VMAT2 was absent from Langerhans cell histiocytosis. VMAT2 is an excellent marker for normal and neoplastic mast cells. The expression of VMAT2 demonstrates the capacity of mast cells for monoamine storage and handling. The presence of VMAT2 in epidermal Langerhans cells revealed a previously unrecognized monoamine-handling phenotype of these cells and indicates possible involvement of amine storage and release associated with antigen presentation. Absence of VMAT2 in neoplastic Langerhans cells indicates a loss of monoamine handling capacity of these cells during tumorigenesis.

Sinus histiocytosis with massive lymphadenopathy and Langerhans cell histiocytosis express the cellular adhesion molecule CD31.

Context.-We investigated expression of the adhesion molecule CD31 in sinus histiocytosis with massive lymphadenopathy (SHML) and Langerhans cell histiocytosis (LCH) because (1) SHML and LCH cells express a variety of cellular adhesion molecules and (2) SHML has been characterized as a reactive histiocytic proliferation, and tissue macrophages (histiocytes) are known to express CD31. Objective.-The purpose of this study was to determine whether SHML and LCH cells express CD31 and whether dual staining with CD31 and S100 facilitates diagnosis of these disease states. Methods.-Formalin-fixed, paraffin-embedded archival tissues were immunohistochemically stained via the labeled streptavidin-biotin method using antibodies against CD31 and S100 protein after heat-induced epitope retrieval. Archival tissues included SHML (n = 2), LCH (n = 10), malignant melanoma (n = 5), sinus hyperplasia (n = 4), granulomas (n = 4), granular cell tumor (n = 6), and normal skin (n = 4). Results.-Normal Langerhans cells in the epidermis were CD31(-)/S100(+); neoplastic Langerhans cells in LCH were CD31(+)/S100(+). Histiocytes in granulomas and in sinus hyperplasia were CD31(+)/S100(-); abnormal histiocytes in SHML were CD31(+)/S100(+). S100(+) tumors (malignant melanoma and granular cell tumor) were CD31(-). Conclusions.-The spectrum of cell types that express CD31 is expanded to include SHML and LCH. We speculate that up-regulation of CD31 in neoplastic Langerhans cells contributes to the migratory capability of LCH cells. CD31 may be a useful nonlysosomal marker of macrophages and their neoplastic counterparts (true histiocytic sarcomas). An immunohistochemical staining panel that includes CD31 and S100 facilitates the diagnosis of SHML and LCH.

Identical rearrangement of immunoglobulin heavy chain gene in neoplastic Langerhans cells and B-lymphocytes: evidence for a common precursor

The coexistence of Langerhans’ cell histiocytosis (LCH) and non-Hogkin’s lymphoma (NHL) has only rarely been reported. In most cases, LCH is found incidentally as a localized lesion in a lymph node involved by NHL. The close topographic association of the two processes in the same node and the frequency of this phenomenon point to a definite relation between them. It is conceivable that, in this situation, LCH represents a specific Langerhans’ cell-mediated, immune-response to lymphoma. Alternatively, focal LCH may be another expression of the abnormalities of the immune system in patients with lymphoma. A third possibility is that, as already shown for other B-cell derived neoplasms [1], a common cell precursor may give rise to both pathological conditions. In mice, development of Langerhans cells (LCs) from a lymphoid-committed precursor has been demonstrated by Anjuere et al. [2] who showed by means of reconstitution experiments that mouse lymphoid-committed precursor are able to generate epidermal LCs, suggesting that the latter are of lymphoid origin. Their study analyzed the capacity of lymphoid cells at different stages of differentiation, namely CD4 low and CD44 + CD25 + pro-T-cell precursors, to form LCs when injected IV in -irradiated mice. In humans, pathological conditions where myeloid and lymphoid diseases coexist represent an useful tool to investigate not only the cellular target of neoplastic lesions but also the existence of progenitor cells with multiple differentiation programs, resulting in phenotypical plasticity [3].

Expression of the monoclonal antibody HECA-452 defined E-selectin ligands in Langerhans cell histiocytosis

The cutaneous lymphocyte associated antigen (CLA) recognized by the monoclonal antibody (moAb) HECA-452 plays a major role in the homing of lymphocyte subpopulations to the skin by binding to E-selectin on dermal microvessels. The factors responsible for the immigration of Langerhans cells (LC) and their precursors into the skin are still unknown, but because normal resting LC are also capable of expressing CLA, the antigen was proposed as a candidate LC-homing structure. To gain insight into these mechanisms, the expression of HECA-452 on neoplastic LC within and outside the skin was investigated in paraffin-embedded sections from 44 patients with localized and disseminated forms of Langerhans cell histiocytosis (LCH) presenting with proliferating cells positive for CD45, CD1a, S100 and HLA-DR. Irrespective of the clinical presentation or the type of organ involved, HECA-452 positive LC were detected in all biopsies tested (range 5->90%). The most prominent HECA-452 reactivity was observed in skin lesions and in areas with accumulations of eosinophilic granulocytes. Our data provide evidence for heterogeneous expression of sLex/sLea structures in various stages of activated and/or differentiated LCH cells. Remarkably, CLA-antigen expression on LCH-cells was not restricted to cutaneous sites. In view of recent findings on the expression of HECA-452 on resting epidermal LC, our data are compatible with the view that local cytokine production by keratinocytes or cells from the surrounding infiltrate induce and/or modulate CLA expression on LC in both cutaneous and extra-cutaneous sites.

Biochemistry and Biology of the Langerhans Cell

Langerhans cells mainly present in the normal epidermis and are thought to be identical to the proliferating cells in the lesions of histiocytosis-X. The Langerhans cell is positive not only for ATPase, esterase, and acid phosphatase, but also for S-100 protein. Since these findings are similar but distinct from those of monocytes and macrophages, the Langerhans cell may be a cell line independent of the monocyte-macrophage system, designated as T-zone histiocytes. Immunologically, the Langerhans cell has Fc and C3 receptors and Ia-like antigen. Thus, the Langerhans cell may be a member of the immune network, as antigen-presenting cells, in the epidermis. One hypothesis is that Langerhans cells activated by external stimuli induce a local immune reaction by activation and proliferation of T-cells, with the interaction of keratinocytes and macrophages. Because of cytochemical and immunologic similarities between Langerhans cells and histiocytosis-X cells, histiocytosis-X may be a proliferative disorder of immature or neoplastic Langerhans cells.