Abundant expression of CD40 and CD40-ligand (CD154) in paediatric Langerhans cell histiocytosis lesions.

The pathogenesis of Langerhans cell histiocytosis (LCH) is obscure, partly because the events leading to activation of Langerhans-like lesional cells (LCH cells) and associated T cells, and the excessive cytokine production by these cells are unknown. The interaction between CD40 on antigen-presenting cells (APC) like Langerhans cells and CD40 ligand (CD40L) (CD154) expressed by activated CD4+ T cells, is essential for the activation of both the APC and the T cells and results in upregulation of APC functions and initiation of immunoreactivity. The effects of CD40-CD40L interaction include increased expression of co-stimulatory and adhesion molecules, proliferation, and production of pro-inflammatory cytokines and proteolytic enzymes, all features of LCH. Using immunohistochemistry, we analysed the in situ presence of the co-stimulatory molecules CD40 and CD40L in 15 fresh frozen biopsies of LCH lesions in children. The cells producing these molecules were identified by double staining for CD1a on LCH cells and CD3 on T cells. Prominent expression of CD40 by LCH cells and CD40L by T cells was found in all 15 specimens regardless of the source of specimen or characteristics of the patient. The findings of high expression of CD40 and CD40L in all specimens imply a key role for the CD40-CD40L adhesion pathway in the pathogenesis of LCH. Since this interaction is an accessible and realistic target for immunotherapy, these findings prompt speculation on the use of blocking antibodies to CD40 or to CD40L in the treatment of LCH.

Differential In situ cytokine profiles of Langerhans-like cells and T cells in Langerhans cell histiocytosis: abundant expression of cytokines relevant to disease and treatment.

The pathogenesis of Langerhans cell histiocytosis (LCH) remains poorly understood. To further elucidate LCH pathogenesis, we analyzed the expression of 10 cytokines relevant to cellular recruitment and activation at the protein level in 14 patients and identified the lesional cells responsible for cytokine production in situ by immunohistochemistry. The cytokines investigated included the hematopoietic growth factors interleukin-3 (IL-3), IL-7, and granulocyte-macrophage colony-stimulating factor (GM-CSF); the lymphocyte regulatory cytokines IL-2, IL-4, and IL-10; the inflammatory regulators IL-1alpha and tumor necrosis factor-alpha (TNF-alpha); and the effector cell-activating cytokines IL-5 and interferon-gamma (IFN-gamma). In all specimens, CD1a(+) histiocytes (LCH cells) and CD3(+) T cells produced large amounts of cytokines, creating a true cytokine storm. IL-2, IL-4, IL-5, and TNF-alpha were produced exclusively by T cells, whereas only IL-1alpha was produced by LCH cells. Equal numbers of LCH cells, T cells, and macrophages produced GM-CSF and IFN-gamma. Equal numbers of LCH cells and macrophages produced IL-10, whereas IL-3 was produced by T cells and macrophages. IL-7 was only produced by macrophages. Eosinophils, present in some specimens, were partially responsible for the production of IL-5, IFN-gamma, GM-CSF, IL-10, IL-3, and IL-7. Expression of all cytokines, abundant in most biopsies, was irrespective of age, gender, or site of biopsy. These findings emphasize the role of T cells in LCH. The juxtaposition of T cells and LCH cells suggests that both cells interact in a cytokine amplification cascade, resulting from stimulation of autocrine and paracrine stimulatory loops. This cascade can be linked directly to the development of LCH through recruitment, maturation, and proliferation of LCH cells. The cytokines studied are known to be involved in the development of other characteristic features of LCH, such as fibrosis, necrosis, and osteolysis.

Behavior of vital and killed autologous pericardium in the descending aorta of sheep.

OBJECTIVES: Cardiovascular implants of fresh autologous pericardium produced mixed results including fibrosis with retraction or thinning and dilatation. The reasons for these differences are unknown but may involve activation of cells intrinsic to the tissue implant. To better understand the behavior of autologous pericardial implants, we studied the outcomes of vital pericardium (fresh) versus ethanol-killed pericardium. METHODS: Fresh and ethanol-killed autologous pericardium was transplanted as a patch, a conduit, or a rectangular flap bisecting the lumen in the descending aorta of sheep. The implants, recovered at 1, 5, 10, 15, and 30 days, were evaluated macroscopically and microscopically and by immunohistologic studies. RESULTS: Fresh implants showed good preservation with fibrin deposition on day 15. Microscopically, cells positive for alpha-actin and von Willebrand-related antigen appeared in the fibrin by day 10. By day 30 the flap was fibrotic and retracted whereas the patch and conduit retained their original appearance on the luminal aspect. An endothelium-like layer expressing von Willebrand-related antigen was present in the patch and conduit but absent in the flap. In contrast, the ethanol-killed implants were free of fibrin by day 10. By day 30, there were no signs of fibrosis or retraction, and a surface layer of cells expressing von Willebrand-related antigen, characteristic of endothelial cells, was present on all implants. All ethanol-killed implants were repopulated by host cells. CONCLUSION: The transluminal flap is an interesting model for studying the behavior of intraluminal autologous pericardial cardiovascular implants. Killing of the pericardial implants alleviated the fibrosis and tissue retraction observed with fresh flap implants.

An unusual histiocytic disorder responding to cyclosporine therapy: a case report.

PURPOSE: To describe the clinical and pathologic presentation and course of a 7-week-old girl with anemia, thrombocytopenia, and organomegaly who was found to have a histiocytic disorder distinct from previously reported cases. METHODS: Bone marrow specimens were studied with conventional methods. A liver biopsy specimen was evaluated by routine and immunohistochemical methods and electron microscopy. RESULTS: The patient was found to have a unique histiocytic disorder in which lesional cells displayed an atypical phenotype. Cyclosporine therapy was associated with a prompt, complete, and apparently permanent resolution of disease. CONCLUSION: This case appears to represent an atypical histiocytic disorder with unique clinical and pathologic features. The disorder resolved after the initiation of cyclosporine therapy.

Nosology and pathology of Langerhans cell histiocytosis.

The pathology of LCH is continuing to be defined and diagnostic features clarified as unprecedented research is done. Although the etiology of LCH remains unknown, new information on cytokines, viruses, immunologic dysfunction, cell surface antigen expression, and clonality in the disease are providing essential pieces of the puzzle.

Central nervous system disease in Langerhans cell histiocytosis.

Central nervous system (CNS) disease in Langerhans cell histiocytosis (LCH) is a poorly understood complication of yet unknown frequency. By far the most common manifestation is in the hypothalamic-pituitary system with diabetes insipidus as the leading sign, followed by other endocrinopathies and hypothalamic dysfunction. However, essentially all other parts of the CNS may be involved. On the one hand, space-occupying histiocytic infiltrates may lead to size- and site-depending symptoms, extending from adjacent bone lesions or arising from the meninges or choroid plexus. On the other hand, a progressive neurological deterioration can occur with mainly cerebellar-pontine symptoms. In this article, these clinical patterns are described in correlation with the morphology on MR imaging and histopathology. Further, the therapeutic strategies are reviewed critically, and guidelines for the management of patients with LCH-related CNS disease are presented.

The relation of Langerhans cell histiocytosis to acute leukemia, lymphomas, and other solid tumors. The LCH-Malignancy Study Group of the Histiocyte Society.

The frequency of Langerhans cell histiocytosis (LCH) and a malignant neoplasm occurring in the same individual appears to be greater than previously recognized. To define the occurrence and the pattern of these events, a Study Group of the Histiocyte Society initiated a registry of patients in whom this association occurred synchronously or asynchronously. Evaluation of 54 patients detected two patterns of associations between LCH and other disorders. First, it is possible that therapy of LCH promotes a secondary malignancy. Second, it is possible that a genetic predisposition, with or without the immunosuppression associated therapy for the malignancy, plays a role in the development and expression of disseminated LCH. Data collected by the LCH-Malignancy Study Group may provide insights into the etiology and pathophysiology of LCH.

Contemporary classification of histiocytic disorders. The WHO Committee On Histiocytic/Reticulum Cell Proliferations. Reclassification Working Group of the Histiocyte Society.

Pathologists and pediatric hematologist/ oncologists of the World Health Organization's Committee on Histiocytic/Reticulum Cell Proliferations and the Reclassification Working Group of the Histiocyte Society present a classification of the histiocytic disorders that primarily affect children. Nosology, based on the lineage of lesional cells and biological behavior, is related to the ontogeny of histiocytes (macrophages and dendritic cells of the immune system). Dendritic cell-related disorders of varied biological behavior are dominated by Langerhans cell histiocytosis, but separate secondary proliferations of dendritic cells must be differentiated. Juvenile xanthogranuloma represents a disorder of dermal dendrocytes, another dendritic cell of skin. The hemophagocytic syndromes are the most common of the macrophage-related disorders of varied biological behavior. Guidelines for distinguishing the exceedingly rare malignant diseases of histiocytes from large cell lymphomas through the use of a battery of special studies are provided.

Langerhans cell histiocytosis of lymph nodes: a morphological assessment of 43 biopsies.

The morphology of Langerhans cell histiocytosis (LCH) involving lymph nodes was analyzed in 43 biopsies from 39 patients and findings were correlated with clinical data. Five histological motifs were recognized: sinusoidal, limited sinusoidal, epithelioid granulomatous, partial effacement, and total effacement. Lesions were composed of histiocytes of the Langerhans cell (LC) family, macrophages, multinucleated giant histiocytes, T lymphocytes, and eosinophils in varying proportions. Proliferative fractions ranged from 2.6 to 48% and 2 of 25 specimens showed a hyperdiploid aneuploid DNA ploidy profile. Epithelioid granulomas composed of histiocytes with the LC phenotype dominated three abdominal specimens, reflecting a picture of LCH not previously reported. Total effacement seen in three patients, was associated with unmarked histiocytoid cells, high proliferative fraction, aneuploid DNA ploidy profile, and, in two, a fatal outcome. Different histologic appearances in lesions from separate sites of the same patient were seen in the cases with epithelioid granulomas and in those with total effacement. The diverse histopathology in lymph nodes involved by LCH is considered in the context of current knowledge of this enigmatic disease.

Histopathology of the liver in histiocytosis syndromes.

Liver biopsies were studied in 47 cases representing various histiocytosis syndromes. These included 32 cases of hemophagocytic syndrome, 11 cases of Langerhans cell histiocysis (LCH), and 4 cases of other histiocytic disorders. All cases of hemophagocytic syndrome, except one with cytomegalovirus infection, displayed portal lymphohistiocytic infiltrates dominated by T lymphocytes. Activation of the hepatic mononuclear phagocytic system (MPS), evidenced by enlarged von Kupffer cells, some of which were hemophagocytic, was seen in 28 cases of hemophagocytic syndrome. Endothelial enlargement, minor degrees of hepatocellular degeneration, and steatosis were also noted. Ten of the 11 cases of LCH also showed activation of the MPS. It was the only lesion in two biopsies. Seven cases demonstrated nonspecific "triaditis." In three this was associated with cholangiocentric and random acinar histiocytic lesions. Evidence of activation of the MPS was also observed in both cases of Rosai-Dorfman disease and was accompanied by acinar histiocytic lesions in one and triaditis in the other. Likewise, both cases of juvenile xanthogranuloma showed activation of the MPS and focal granulomatous lesions. It is concluded that activation of the MPS is a common feature of liver disease in histiocytosis syndromes and that hepatic enlargement may be the result of this process instead of, or in addition to, the liver lesions known to be featured in these disorders. Hepatic lesions of the various histiocytosis syndromes resemble typical lesions in other sites and, in some instances, are accompanied by nonspecific changes. These nonspecific changes may occur in the absence of lesions that are diagnostic or typical of the particular histiocytosis syndrome. The location and character of hepatic lesions are important factors in the significance of liver involvement.

The histopathology of Langerhans cell histiocytosis.

Selected aspects of the histopathology of Langerhans cell histiocytosis representing diagnostic difficulty and/or controversy are presented with emphasis on the composition of pathological lesions. Lesional cell phenotypes and the factors influencing variations are noted. Features of several skin-based histiocytic disorders, dermatopathic lymphadenopathy and Rosai-Dorfman disease are compared. Associations between Langerhans cell histiocytosis and juvenile xanthogranuloma and malignant disorders are considered. Observations of potential significance in the eventual elucidation of the pathogenesis of these enigmatic diseases are presented.

Central nervous system disease in Langerhans cell histiocytosis.

Diabetes insipidus and anterior pituitary dysfunction, are familiar central nervous system (CNS) complications of Langerhans cell histiocytosis (LCH) but the pathophysiology and biological behaviour of other forms of CNS involvement in LCH are poorly understood. In an attempt to improve our understanding of these rare complications, we studied 23 patients with LCH in whom neuroradiological abnormalities, with or without neurological dysfunction other than diabetes insipidus, developed during the course of disease. Neuroradiological abnormalities were of three basic types (a) poorly-defined changes in white matter, (b) well-defined changes in white and grey matter and (c) extra-parenchymal "tumoural" masses. There was a profusion of associated neurological signs and symptoms in most cases but some patients were asymptomatic. The neuropathological features were complex but infiltration of the CNS by histiocytes with xanthomatous change, particularly prominent in mass lesions, was common in the 13 cases in which biopsies were done. Patients with lytic lesions of the skull and diabetes insipidus are evidently most at risk of developing these rare manifestations of LCH. Therapeutic questions could not be answered from this study because no standard treatment had been given and outcome varied widely.

Langerhans'-cell histiocytosis (histiocytosis X)--a clonal proliferative disease.

BACKGROUND: The lesions of Langerhans'-cell histiocytosis (histiocytosis X), a proliferative histiocytic disorder of unknown cause, contain histiocytes similar in phenotype to dendritic Langerhans' cells. The disease ranges in severity from a fatal leukemia-like disorder to an isolated lytic lesion of bone. Intermediate forms of the disease are usually characterized by multiorgan involvement, diabetes insipidus, and a chronic course. METHODS: To determine whether Langerhans' histiocytosis is a polyclonal reactive disease or a clonal disorder, we used X-linked polymorphic DNA probes (HUMARA, PGK, M27 beta[DXS255], and HPRT) to assess clonality in lesional tissues and control leukocytes from 10 female patients with various forms of the disease. Lymphoid clonality was also assessed by analysis of rearrangements at immunoglobulin and T-cell-receptor gene loci. RESULTS: The HUMARA assay detected clonal cells in the lesions of 9 of the 10 patients: 3 patients had acute disseminated disease, 3 had unifocal disease, and 3 had intermediate forms. The percentage of clonal cells closely approximated the percentage of CD1a-positive histiocytes in each lesion. Clonality was also confirmed in two of nine cases with the PGK or M27 beta probe. Extreme constitutional lyonization precluded assessment of clonality in the 10th case. Lymphoid clonality was ruled out in all cases. CONCLUSIONS: The detection of clonal histiocytes in all forms of Langerhans'-cell histiocytosis indicates that this disease is probably a clonal neoplastic disorder with highly variable biologic behavior. Thus, genetic mutations that promote clonal expansion of Langerhans' cells or their precursors may now be identified.

Acute leukemia in association with Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH) and malignancy occurring in the same individual is unusual and has generally been the subject of isolated case reports. To better define the occurrence of these events a registry of cases with synchronous or asynchronous LCH and malignancy was developed with the cooperation of the Histiocyte Society. In 1991 the Histiocyte Society surveyed its members requesting information on cases in which LCH was associated with malignancy. The questionnaire was mailed to all members of the society and specifically requested information on the clinical and laboratory features of the cases, disease evolution, and response to therapy. Retrospective reporting was allowed. With this initial data, an ongoing registry of LCH patients with associated malignancy was begun of such cases, including evolution and response to therapy. Twenty-seven patients were enrolled during the first year of registry, of whom 4 patients had the association of LCH with a malignant lymphoma and 10 cases had an association of LCH with other types of solid tumor. The remaining 13 patients had the association of LCH with acute leukemia. In five cases, LCH was associated with acute lymphoblastic leukemia FAB L1 (ALL). In four cases the ALL preceded the LCH by 6 months to 1 year. In four of five patients the LCH was localized; in two instances the LCH was treated with chemotherapy. In all cases the leukemia was treated according to local standard ALL protocols and in one case autologous bone marrow transplantation (ABMT) was performed at relapse. Three patients are free of leukemia, one of whom has persistent localized LCH of the skin. Two patients died of the ALL, one of whom was free of the LCH at the time of death. In eight instances LCH was reported in association with acute myeloid leukemia (AML). Six of these patients had a generalized form of LCH. In seven the diagnosis of LCH preceded the diagnosis of leukemia by more than 2 years (median 4 years). In the remaining patient both diagnoses were made concurrently. In all seven cases in whom LCH was the initial diagnosis the treatment consisted of chemotherapy and/or radiotherapy. Seven patients died from the AML, five without evidence of LCH. The temporal patterns of the LCH-ALL and LCH-AML associations are distinct with ALL usually preceding the diagnosis of LCH and AML succeeding it.(ABSTRACT TRUNCATED AT 400 WORDS)

Langerhans' cell histiocytosis (histiocytosis X): immunophenotype and growth fraction.

The immunophenotype and proliferation fraction have been investigated in 26 cases of Langerhans' cell histiocytosis (LCH). In all cases LCH cells were positive for S-100 protein, CD1a, or both. In most cases LCH cells expressed the macrophage-associated marker CD68 and in two cases they contained lysozyme. Expression of both cytoplasmic CD2 and CD3 was observed in cryostat sections. An unexpected finding was the presence of placental alkaline phosphatase in LCH cells. Langerhans' cells in normal skin were negative for both CD2 and CD3, but a proportion contained placental alkaline phosphatase. In four cases of Rosai-Dorfman disease the histiocytic cells, which share certain immunophenotypic properties with Langerhans' cells, also were positive for placental alkaline phosphatase. A significant proportion of LCH cells stained positively with the antibody to proliferating cell nuclear antigen and also with the proliferation marker Ki-S1. A good correlation between the percentage of Ki-67-positive and proliferating cell nuclear antigen- and Ki-S1-positive cells, respectively, was observed. Thus, in comparison with their putative precursors, LCH cells have an aberrant phenotype and are proliferating locally. This might suggest that LCH is a neoplastic rather than a reactive process.

Hemophagocytic lymphohistiocytosis: a hemophagocytic syndrome.

Hemophagocytic lymphohistiocytosis, terminology that designates a syndrome that may be familial or sporadic, with or without an associated viral infection, is presented as the prototype of a hemophagocytic syndrome, a condition in which there is uncontrolled activation of the cellular immune system. Diagnostic criteria include idiopathic fever, splenomegaly, cytopenias, hypertriglyceridemia, hypofibrinogenemia, and the presence of hemophagocytosis. The surgical and autopsy pathology features infiltrates composed of lymphocytes and ordinary, but activated, histiocytes and hemophagocytosis. The chronic hepatitis-like hepatic lesion is noted to be characteristic, if not unique, in this age group and setting. Current concepts of pathophysiology focus on the role of cytokines, particularly interleukin (IL)-1, IL-2, soluble IL-2 receptor, plasminogen activator, and prostaglandins. The clinicopathologic features of the syndrome can be accounted for by the uncontrolled and unopposed production and release of these mediators. Nosology places hemophagocytic lymphohistiocytosis in the position of the most important of the "benign" histiocytosis syndromes that involve ordinary histiocytes of the mononuclear phagocytic system in contrast to Langerhans cell histiocytosis (histiocytosis X) in which pathological dendritic histiocytes are operative. Features that distinguish hemophagocytic lymphohistiocytosis from other disorders, such as malignant histiocytosis, X-linked lymphoproliferative disorder, congenital immunodeficiency states, the accelerated phase of Chediak-Higashi syndrome, and cytophagic histiocytic panniculitis, which may be associated with a hemophagocytic syndrome, are presented.