Disease Information for Linear IGA dermatosis

Linear immunoglobulin A (IgA) dermatosis (LAD) is an autoimmune subepidermal vesiculobullous disease that may be idiopathic or drug-induced; Children and adults are affected, with disease of the former historically referred to as chronic bullous dermatosis of childhood; The clinical presentation is heterogeneous and appears similar to other blistering diseases, such as bullous pemphigoid and dermatitis herpetiformis; LAD is an autoimmune disease histopathologically characterized by the linear deposition of IgA at the basement membrane zone (BMZ); Antibody deposition leads to complement activation and neutrophil chemotaxis, which eventuates in loss of adhesion at the dermal-epidermal junction and in blister formation; Disease in children is immunologically identical to that of adults; The mechanism of loss of self-tolerance to target antigens is unknown; Within the dermal-epidermal junction, different antigenic target sites, including the lamina lucida, the sublamina densa, or both locations simultaneously, have been identified; The best-characterized antigen is a 97-kd protein extracted from human epidermis that binds IgA antibodies from sera of patients with LAD; Sera that binds the 97-kd antigen localizes to the lamina lucida of salt-split skin; Originally thought to be a unique protein of the lamina lucida, recent work reveals that the 97-kd protein may represent a portion of the extracellular domain of the 180-kd bullous pemphigoid antigen (BPAg2);

A 285-kd target antigen has been identified in the lamina lucida and the sublamina densa; this antigen is recognized by circulating antibodies in some patients with LAD, but it has not been further characterized; A 250-kd dermal antigen corresponding to collagen VII of anchoring fibrils has also been reported as a target antigen in some patients;

LAD illustrates the importance of identifying the target antigen; In cases where type VII collagen is the molecule against which the antibody response is directed, patients are less likely to be responsive to treatment; Thus, viewing this condition as a subset of epidermolysis bullosa acquisita is better; Similarly, patients with antibodies directed against the bullous pemphigoid antigens may be classified as having bullous pemphigoid but with an IgA response rather than an IgG response; The mean duration of idiopathic LAD of childhood is 3_9 years, ranging from 2_ 1 to 7_9 years; Remission has been reported to occur in 64% of children, in most cases within 2 years; Disease of adults is more protracted, with a mean duration of 5_6 years, lasting anywhere from 1-15 years; The remission rate in adults is less than that in children (48%); The disease tends to wax and wane in severity; Drug-induced cases typically resolve quickly once the causative agent is identified and withdrawn; Cutaneous lesions usually heal without scarring;

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