Linear IgA bullous dermatosis is characterized by IgA autoantibodies reactive with LAD-1 and LABD97, truncated forms of BP180 (type XVII collagen), but not with full-length BP180.Toyonaga et al. determined that cleavage within both the C-terminal region and NC16A domain plays a role in exposure of neoepitopes on the 15th collagenous domain of BP180.
Autoantibodies against collagen XVII (BP180) are seen in bullous pemphigoid, pemphigoid gestationis, mucous membrane pemphigoid, linear IgA disease, lichen planus pemphigoides and pemphigoid nodularis.
For immunolabeling, we used two recently developed monoclonal antibodies to LAD-1 whose epitopes were ultrastructurally localized in the lamina lucida between NC16A and carboxyterminal domains of BPAG2, as well as autoantibodies against LAD-1 from the sera of two patients with linear IgA dermatosis.
Bullous pemphigoid and linear IgA dermatosis sera recognize a similar 120-kDa keratinocyte collagenous glycoprotein with antigenic cross-reactivity to BP180.
The anchoring filament protein LAD-1 has been recently identified as the target of autoantibodies in the acquired blistering disorder linear IgA bullous dermatosis.