Pathophysiology of Autoimmune Bullous Diseases

In immunobullous disease, the host immune system disrupts adhesive interactions in the skin, typically leading to clinical blister formation. The pathophysiology of these diseases has been an active area of investigation. The mechanisms by which these disorders lead to loss of adhesion are variable and disease dependent; however, general principles have been described. The term ‘‘subepidermal blistering disease’’ applies to several disorders that share the clinical appearance of vesicles and bulla, the histologic finding of subepidermal blistering, and in situ deposition of autoantibodies at the dermal–epidermal junction. This group of diseases includes bullous pemphigoid (BP), cicatricial pemphigoid, herpes gestationis, dermatitis herpetiformis, linear IgA disease, lichen planus pemphigoides, epidermolysis bullosa acquisita (EBA), and bullous systemic lupus erythematosus. Intraepidermal blistering diseases are characterized by acantholysis, loss of adhesion between adjacent epidermal keratinocytes, and deposition of immunoreactants at the keratinocyte cell membrane. The protypical intraepidermal autoimmune blistering diseases are pemphigus vulgaris (PV) and pemphigus foliaceus (PF). The autoimmune nature of these disorders began to be appreciated in the late 1960s when Jordon and Beutner used immunofluorescent techniques to demonstrate that BP patients have circulating and tissue-bound autoantibodies directed against antigens of the basement membrane zone. Use of these autoantibodies as a screening tool facilitated the identification of the target autoantigens. Using such an approach, Stanley et al. (1981, 1988) first characterized BP antigens at the molecular level and cloned the BP230 cDNA. Subsequently, cDNAs encoding BP180 (the autoantigen for BP, cicatricial pemphigoid, herpes gestationis, lichen planus pemphigoides, and linear IgA disease), laminin 5 (the autoantigen for cicatricial pemphigoid), and type VII collagen (the autoantigen for EBA and bullous systemic lupus erythematosus) were also cloned and characterized.