Epidermal Langerhans' cells in Behçet's disease

Immunopathogenesis of Behçet Disease

BACKGROUND

Behçet's Disease (BD, OMIM 109650) is a chronic relapsing inflammatory disease of unknown etiology with unpredictable exacerbations and remissions. First described in 1937 by the Turkish dermatologist HulusiBehçet, as a trisympton complex (oral and genital ulcers and uveitis), it is now recognized as a multisystemic disease. The syndrome can manifest in diverse ways and can involve nearly every organ system. Several studies have implicated T cells and monocytes in the pathogenesis of BD especially when these cells are stimulated by heat shock proteins and streptococcal antigen. This article presents a review of the relevant published literature about the immunopathogenesis of BD.

RESULT

The authors used MeSH terms "Behçet's disease" with "pathophysiology," "pathogenesis," "genetic", "epigenetic", "immunogenetic" or "immune response" to search the PubMed database. All the relevant studies identified were included.

Immunopathogenesis of ocular Behçet's disease

Behçet's disease (BD) is a chronic recurrent systemic inflammatory disorder of unknown etiology characterized by oral and genital ulcerations, skin lesions, and uveitis. The ocular involvement of BD, or Behçet's uveitis (BU), is characterized by panuveitis or posterior uveitis with occlusive retinal vasculitis and tends to be more recurrent and sight threatening than other endogenous autoimmune uveitides, despite aggressive immunosuppression. Although pathogenesis of BD is unclear, researches have revealed that immunological aberrations may be the cornerstone of BD development. General hypothesis of BD pathogenesis is that inflammatory response is initiated by infectious agents or autoantigens in patients with predisposing genetic factors and perpetuated by both innate and acquired immunity. In addition, a network of immune mediators plays a substantial role in the inflammatory cascade. Recently, we found that the immunopathogenesis of BU is distinct from other autoimmune uveitides regarding intraocular effector cell profiles, maturation markers of dendritic cells, and the cytokine/chemokine environment. In addition, accumulating evidence indicates the involvement of Th17 cells in BD and BU. Recent studies on genetics and biologics therapies in refractory BU also support the immunological association with the pathogenesis of BU. In this review, we provide an overview of novel findings regarding the immunopathogenesis of BU.

Contact sensitivity in Behçet's disease

CONTEXT

Behçet's disease (BD) is a multisystemic inflammatory disorder with unknown etiology. Many immunological changes were reported in BD previously and these changes may affect the frequency of contact sensitivity in these patients.

OBJECTIVE

We aimed to identify whether there is an interaction between contact sensitivity and BD.

METHODS

The 'European standard series' with 27 allergens were performed on the upper backs of patients and healthy volunteers according to international standards using the IQ-Chamber. The test-units which contain these allergens were removed after 2 days. According to International Contact Dermatitis Research Group Recommendations test areas were evaluated on days 2, 3 and 7 to detect any delayed allergic reactions. The results of both groups were compared by using chi-square test.

RESULTS

One hundred adult persons (50 BDs and 50 healthy controls) were tested. Positive patch test reaction to 1 or more allergens was observed in 7 (14%) patients in BD group and in 12 (24%) persons in control group. There was no statistically significant difference between these two groups.

CONCLUSIONS

The frequency of contact sensitivity in BD is not different from healthy persons.

Immunohistochemical and ultrastructural features of Langerhans cells in condyloma acuminatum

BACKGROUND

There are few studies on the abnormal morphology of Langerhans cells (LCs) in condyloma acuminatum (CA) lesions and the essence of the abnormal morphology of LCs in CA lesions is still not well elucidated. The aim of this study was to further investigate the morphological features of LCs in CA lesions.

METHODS

CD1a(+) LCs in 13 CA lesions and in 13 normal controls were labeled using immunohistochemistry and examined by light microscopy. Ultrastructural investigation on LCs in six CA lesions and in six normal controls was performed by electron microscopy.

RESULTS

Compared with those in normal controls, most CD1a(+) LCs in CA lesions exhibited dysplastic dendrities and abnormal distribution. The number of CD1a(+) LCs in CA lesions (26.31 +/- 18.84) was statistically lower (p < 0.001) than that in normal controls (72.00 +/- 27.40). Electron microscopy showed that the number of Birbeck granules within lesional LCs (4.00 +/- 2.94) was significantly decreased (p < 0.001) than that within normal LCs (10.80 +/- 4.78). The ultrastructures of most lesional LCs displayed degenerative changes.

CONCLUSIONS

The morphology of most LCs in CA lesions shows degenerative changes, which suggest that these LCs have been functionally impaired.

Immunopathogenesis of Behçet's disease with special emphasize on the possible role of antigen presenting cells

Behçet's disease (BD) is a systemic vasculitis with unclear etiology and pathogenesis. Although several viral and bacterial causes have been investigated in detail for several years, of late it is widely accepted that microorganisms may play a role as a trigger, or as a cross-reactive antigens that interfere with self-antigens, such as heat-shock proteins. Genes such as HLA-B51, MICA and TNF, considered to play a crucial role in the pathogenesis of BD, are located in the major histocompatibility complex (MHC). However, it has been accepted that, only HLA-B51 is directly related with pathogenesis of the disease, and others have strong linkage disequilibrium with HLA-B51. Some other genes such as IL1, Factor V and ICAM-1, KIR and eNOS assumed to take a part in the pathogenesis are settled out of the MHC region. In patients with BD, several abnormalities in innate and acquired immunity were detected. Mainly, the hypersensitivity of T lymphocytes to different types of antigens plays a critical role in the pathogenesis. However, it is not clear that whether defective signal transduction or antigen presenting cell (APC) dysfunction is responsible for T cell hypersensitivity. Cytokines and chemokines secreted from APCs and T cells are suggested to cause the neutrophil hyperactivation. Activated neutrophils secrete some cytokines, which prime themselves and also stimulate Th1 cells. These relationships among APCs, Th1 lymphocytes and neutrophils constitute the basis of immune responses in BD. In this review, we focus on the possible role of APC in the pathogenesis of BD with an attempt to take attention of researchers in this field to these cells at the crossroads of innate and adaptive immunity, and discuss other potential contributors including cells of the immune system and mediators.

Rod-shaped bodies resembling birbeck granule-like structures in endothelial cells of dermal capillaries in generalized granuloma annulare

A previous study demonstrated that, in generalized granuloma annulare in the epidermis, the Langerhans' cell section area and the number of Langerhans' cell granules or Birbeck granules per cell section were increased, suggesting an active state of these Langerhans' cells. Reexamination by transmission electron microscopy of the same tissue, but in samples also containing dermal tissue, from the same subjects revealed endothelial cells with rod-shaped bodies resembling Birbeck granules or Birbeck granule-like structures. This finding has not been previously described in blood vessels of human skin and is described here.

Langerhans' cells of elderly patients with decubital ulcers

An ultrastructural and morphometric study compared Langerhans' cells in sacral epidermis, 8-10 cm from the lesion of patients (mean age 70) with decubital ulcers, with those in the patients' own normal epidermis from the upper leg and with those in the epidermis from the upper leg of normal age-matched volunteers. The Langerhans' cell section area was significantly lower in patients' control leg epidermis (25.86 +/- 2.29 microns2) than in that from normal controls (35.74 +/- 3.76 microns2) or that from patients' sacral epidermis near the lesion (41.26 +/- 3.45). The number of Langerhans' cell granules was higher in control leg epidermis of patients (10.22 +/- 1.26) and was significantly higher in lesioned sacral epidermis (12.94 +/- 1.90) than in normal controls (6.97 +/- 1.47). In Langerhans' cells in patients' epidermis, formative stages of Langerhans' cell granules were observed. The findings may indicate that Langerhans' cells in patients' epidermis are in an active state.

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.

Epidermal Langerhans cells in patients with primary Sjögren's syndrome

IgG-binding to the surface of Langerhans cells (LC) is a feature of primary Sjögren's syndrome and might be associated with qualitative and quantitative defects in LC. Fifteen patients with primary Sjögren's syndrome and 15 healthy controls had a punch biopsy performed from clinically unaffected skin. LC were enumerated in epidermal sheets by an immunoperoxidase technique, as well as demonstrated by immunofluorescence in vertical sections, which were furthermore examined for in vivo deposits of immunoglobulins, fibrinogen and C3. A significant (P less than 0.05) reduction in number of LC, measured on epidermal sheets, was found in patients as compared with controls. Examination of vertical sections did not reveal abnormalities in morphology or localisation of epidermal LC. Intraepidermal IgG deposits were demonstrated in 7/15 patients. In vivo deposits were not found in any of the controls. The density of epidermal LC was not correlated to the presence of intraepidermal IgG deposits.