Auto-immune mechanisms as a probable aetiology of Behh

Angiographic Findings of Great Vessel Involvement in Behçet's Disease

Behçet's disease (BD) is a systemic disorder and vasculitis is a common pathologic finding that may give clues in the understanding of the vascular involvement. During the period between 1968 and 1988, 30 patients with BD had vascular complications that were diagnosed by conventional venography (indud ing cavography) (in 15 patients prior to 1985) and then by computed tomography, digital subtraction angiography (DSA), and sonography in the remaining 15 patients for the last four years . The group included 13 patients with superior vena caval obstruction (SVCO), 3 with inferior vena caval obstruction (IVCO), 4 with both SVCO and IVCO, 2 with IVCO and hepatic veins obstruction (Budd-Chiari syndrome, BCS), 1 patient with SVCO, IVCO, and BCS, 1 with BCS, 1 with portal vein and IVCO, 4 patients pulmonary artery occlusion (1 of them also had pulmonary artery aneurysm), and finally, 1 patient with right illiac artery aneurysm. In many cases, classical clinical features of BD were not evident when great vessels were involved.

The authors concluded that DSA and sonography are the preferred method in demonstrating vascular complications of BD and that BD should be taken into consideration when a patient presents with a great vessel involvement due to unknown cause.

Budd-Chiari syndrome: analysis of 30 cases

The authors report their experience with 30 adult patients with Budd-Chiari syndrome (BCS), which is a rare and serious disorder, characterized by hepatic outflow obstruction caused by many different conditions. The diagnosis was based on the clinical data, ultrasonography (US), vena cavography and hepatic venography, computed tomography (CT), and liver biopsy. Behçet's disease (BD) was found in 10 patients with BCS as an underlying disease. Two patients used oral contraceptive drugs, 2 had liver tumor hepatocellular carcinoma and liver lymphoma, and 1 patient had chronic lymphocytic leukemia. Despite full investigation, the authors could not find any obvious underlying cause in the other 15 patients. The results suggest that (1) BCS must be considered as a possible complication in patients with Behçet's disease when they have hepatomegaly even if there were no cardinal manifestations of the disease at the time of admission, and BD is the most common etiologic factor in BCS (33%) in Turkey, where the incidence of Behçet's disease is relatively high. (2) Anti-aggregant treatment seems to be effective in many instances. (3) There were space-occupying lesion-like appearances in the liver of 7 cases by CT and US examination in the acute stage, and these disappeared on the follow-up CT and US in 5 patients but continued in 2. BCS should thus be differentiated from other liver lesions. (4) There were other great-vessel involvements in 43% of the cases, mostly venous, but only 1 pulmonary arterial occlusion.

Langerhans cells: structure, function and role in oral pathological conditions

Langerhans cells (LCs) are dendritic bone marrow derived cells situated suprabasally in most stratified squamous epithelia, such as the epidermis and the epithelium of oral mucosa, including the gingiva. Langerhans cells are thought to act as antigen-presenting cells (APC) during induction of immune responses. The exact role of Langerhans cells in the oral mucosa is not fully understood although several investigations suggest that these cells are involved in reactions to antigen challenge under both normal and pathological situations. In this paper the structure, phenotypic markers and derivation of Langerhans cells are reviewed. In view of recent findings, the immunological characteristics and the implications of Langerhans cells in pathologic oral reactions are discussed.

Possible role of apoptotic cells of the oral epithelium in the pathogenesis of aphthous ulceration

Electron microscopic examination of the normal oral mucosa of patients with recurrent aphthous ulceration or Behçet's syndrome revealed that the degenerate dark prickle cells are apoptotic cells. Such dark prickle cells showed characteristic findings of apoptosis, such as the shrinkage of nucleus and cytoplasm and the formation of contraction vacuoles. The number of intraepithelial mononuclear cells phagocytosing apoptotic cellular debris increased remarkably at the preulcerative stage of the aphthous lesions. The apoptotic debris also attracted neutrophilic leukocytes in the prickle cell layer at the preulcerative stage but not in the normal oral epithelium. It is speculated that the onset of aphthous ulceration is closely related to phagocytosis of these apoptotic cells by intraepithelial mononuclear cells.

Pathomorphologic features of the ulcerative stage of oral aphthous ulcerations

Macroscopic, histopathologic, and immunohistochemical features of eight 1- to 7-day-old minor (Mikulicz) aphthae, one herpetiform ulcer, and one ulcer from a patient with Behcet's syndrome were studied. In addition to light and electron microscopy, methods included the peroxidase-antiperoxidase (PAP) technique to disclose binding of IgA, IgG, IgM, Clq, and C3. Observations revealed the presence and distribution of extravasates of erythrocytes at and around the ulcers, extravascular neutrophilic granulocytes undermining the oral epithelium of the ulcer margin, the presence of numerous macrophages loaded with phagolysosomes containing debris of neutrophilic granulocytes, particular pathomorphologic features of a Behcet lesion and a herpetiform lesion, and the occurrence in diseased and normal oral mucosa of particular stratum spinosum cells binding nonselectively all immune components tested in this study, probably by leakage and passive diffusion of serum proteins. The observations fit the concept of immune complex vasculitis being essential in the pathogenesis of oral aphthous ulcerations.

Quantitative electron microscopy microscopical analysis of leukocyte infiltration in oral ulcers of Behçet's syndrome

A stereological electron microscopical technique was applied to biopsies of oral ulcers from patients with Behçet's syndrome in order to carry out a quantitative analysis of the cellular infiltrate. The results have confirmed the light microscopical qualitative findings of a large number of lymphocytes (67%) but have established that a relatively large proportion of the leukocytes (14%( belong to the monocyte-macrophage series. The virtual absence of plasma cells during the early stages of ulceration and the presence of a large number of lymphocytes and monocytes argue in favour of a type IV cell-mediated immune reaction. As the lesion progresses a type III reaction develops and this might be associated with immune complexes found in the serum of patients with Behçet's syndrome.

Behçet's disease

Behçet's disease is characterized by three primary components: iridocyclitis (historically with hypopyon), aphthous lesions in the mouth, and ulceration of the genitalia. Erythema nodosum, arthropathy and thrombophlebitis often accompany these manifestations, but the ocular symptoms may be the most important and serious manifestations of the disease. Central nervous system involvement, most often due to necrotizing vasculitis, may be the most protean manifestation of the disease, leading to death. The frequency of ocular manifestations is 70-85% in patients with the disease; the underlying disease mechanism in all organ systems is an occlusive vasculitis. Although the most common ocular symptom is that of anterior uveitis, often with hypopyon as a very late sign, the presence of necrotizing retinal vascular lesions is well known and often obscured by the severity of the anterior reaction. Definitions, incidence, clinical characteristics, differential diagnosis, and management of Behçet's ocular disease are discussed, as are the interrelationships of the different organ manifestations. The ophthalmologist should be familiar with the full spectrum of disease presentation since he or she may be the first physician to encounter the Behçet's patient.

The pathomorphology of malignant catarrhal fever. II. Multisystemic epithelial lesions

Epithelia from 18 Holstein-Fresian calves with experimentally induced malignant catarrhal fever and two calves with naturally occurring disease had severe destructive inflammatory epithelial lesions. Calves were necropsied at early, mid and late clinical stages. Multifocal, degenerative and necrotic epithelial lesions were associated with lymphoid cells. Ultrastructurally, numerous lymphocytes, lymphoblasts and macrophages were accumulated between epithelial cells and in lamina propria, vessels and perivascular tissues. Epithelial cells in such lesions had variably severe degenerative changes or were necrotic but there was no proliferative response. Lesions were widespread in all calves and affected oral, ocular, gastrointestinal, ductal, urinary tract, choroid plexus and other epithelial tissues. Calves killed in late clinical stages had more severe lesions than those killed early. The predominantly lymphocytic, invasive-destructive pattern seen in tissues of cattle with malignant catarrhal fever was similar to that seen in such conditions as contact hypersensitivity and graft versus host disease. Viral structures were not seen.

Immunological aspects of recurrent oral ulceration and Behçet's syndrome

Immunological factors play in recurrent oral ulceration (ROU) and Behçet's syndrome (BS) but these cannot be distinguished by means of antibodies and cell-mediated immune responses to oral mucosal antigens. However, HLA markers seem to differentiate ROU from BS. Immune complexes have now been found in about 55% of patients with BS and fewer patients with ROU, so that the transition from the focal ROU to the multifocal BS might be mediated by immune complexes. Immunopathological studies have shown that a vasculitis is the essential lesion in BS and this might be secondary to immune complexes inducing complement activation and damage. It is not clear at present whether the increased levels of C9 and C-reactive protein are a manifestation of acute phase reactants. C9 could be involved in complement dependent lysis and C-reactive protein in modulating the cell-mediated immune responses by its effect on T lymphocytes. It seems that at least two types of damaging immune mechanisms have been identified; cell-mediated and immune complex induced reactions and these might account for the association between ROU and BS.

Electron microscopic study on the pathogenesis of recurrent aphthous ulceration as compared to Behçet's syndrome

In the prickle-cell layer of the oral epithelium of recurrent aphthous ulceration (RAU) the reticuloid cells with homogeneous, electron-lucent nuclei were attached to the degenerated prickle cells and ingested the cytoplasm of the prickle cells. The reticuloid cells came in contact with small lymphocytes, to which the immunologic information was transferred, inducing them to undergo blast transformation. Lymphoid cells, corresponding to T-cells, may produce a cytotoxic factor, since the prickle cells ultimately undergo degeneration. These changes are consistent with those of delayed hypersensitivity reactions. The cytoplasm of prickle cells apparently acts as an autoantigen. In Behçet's syndrome the macrophages were encountered in the epithelium. Other consequences were quite similar to those of RAU. The nucleus of the macrophage is more electron dense and has condensed chromatin along with the nuclear membrane. This can be a difference between Behçet's syndrome and RAU only at the initial stage of the diseases.