The immunopathology of bullous pemphigoid

Intracellular ionic changes induced by bullous pemphigoid IgG subclasses

To ascertain whether membrane signal transduction is induced by bullous pemphigoid (BP) antibody and whether cell lysis is induced by its complement activation, we assessed the intracellular Ca2+ concentration ([Ca2+]i), intracellular pH, membrane potential and morphology of living cells by following the time course of fluorescence intensity of Fluo-3/AM, Snaff-1/AM, Dioc-5 and Luciffer yellow, respectively. A transient increase of Fluo-3 fluorescence intensity in DJM-1 cells (a squamous cell carcinoma line) was revealed when the cells were incubated with 2 of five IgG1 BP antibodies. However, no transient increase of Fluo-3 fluorescence intensity was revealed when the cells were incubated with IgG2 and IgG4 BP antibodies. A transient increase of Fluo-3 fluorescence intensity was revealed in DJM-1 cells incubated with 3 of seven IgG1 and 1 of four IgG2 BP antibodies in an EGTA-containing low-Ca2+ medium. On the other hand, the Dioc-5 fluorescence intensity did not change significantly, though the increase of Fluo-3 fluorescence intensity was observed. The increase of Snarf-1 fluorescence intensity was revealed in DJM-1 cells incubated with 2 of five IgG1 BP antibodies, but was not revealed in the cells incubated with IgG2 or IgG4 of BP antibodies. Study of complement activation by BP IgG1 showed a transient increase of Fluo-3 fluorescence intensity of with 3 of five IgG1 BP antibodies when DJM-1 cells were incubated with complement-supplemented normal-Ca2+ medium. At the same time, however, endocytosis and cell lysis were not observed with 2 IgG1 BP antibodies which did induce an increase of Fluo-3 fluorescence intensity when Lucifer-yellow-loaded DJM-1 cells were incubated with complement-supplemented normal-Ca2+ medium. We examined next whether anti-180 kD BP antigen monoclonal antibodies (mAbs R-223 and 233) induce an increase of Fluo-3 fluorescence intensity. MAb R-223 did not induce any increase of Fluo-3 fluorescence intensity in DJM-1 cells, when incubated with normal- and low-Ca2+ media However, mAb R-223 induced a transient increase of Fluo-3 fluorescence intensity in DJM-1 cells when incubated with complement-supplemented normal-Ca2+ medium. MAb 233 did not induced an increase of Fluo-3 fluorescence intensity in DJM-1 cells when incubated with normal- and low-Ca2+ media. These results suggest that the BP IgG1 induces Ca2+ release from intracellular storage sites, however, the complement activated by BP IgG1 does not induce cell lysis. It could not be confirmed that anti-180 kD BP antigen antibody induced Ca2+ release from intracellular storage sites.

Non-infectious diseases of the oral soft tissue: a new approach

A significant proportion of the non-infectious diseases of oral mucosa are either auto-immune in nature or have lesions which are the result of immunologically-mediated events. These include pemphigus, benign mucous membrane pemphigoid, linear IgA bullous dermatosis, dermatitis herpetiformis, epidermolysis bullosa acquisita, erythema multiforme, and lichen planus. Although each of these has certain specific characteristics, all may produce bullae, erosions, and ulcers on the oral mucosa, resulting in confusingly similar clinical presentations. With careful clinical, histological, and immunofluorescence examination, it is possible to establish a definitive diagnosis in a high proportion of cases. However, one of the most exciting developments which has emerged from recent research into these diseases is their precise molecular characterization. This raises the prospect of accurate, highly specific diagnostic tests which would provide the basis for sound clinical management, with original approaches replacing the somewhat unsatisfactory symptomatic treatment which is often all that is available.

Vesiculo-bullous mucocutaneous disease: benign mucous membrane and bullous pemphigoid

Bullous pemphigoid (BP) and benign mucous membrane pemphigoid (BMMP) are autoimmune diseases characterised by subepithelial bulla formation and showing substantial overlap in clinical signs and symptoms. BP principally involves skin and BMMP the oral mucosa and eyes. The gingiva are affected in 90% of cases of BMMP and buccal mucosa and palate in up to 30%. Lesions may heal with scarring. Extension into the pharynx and esophagus causes sore throat and dysphagia. Severe ocular involvement may cause blindness. Bulla formation is attributed to complement activation, following IgG binding to the basement membrane zone, with subsequent polymorphonuclear leukocyte accumulation. The target antigen in BP is a 180-230 kD protein associated with the basilar membrane of basal keratinocytes. The gene encoding the BP antigen has been partially cloned. It is likely that the same antigen is involved in BMMP, but the mechanism of scarring is not understood. Treatment of BP and BMMP includes systemic steroid and azathioprine therapy and topical steroids.