Bullous systemic lupus erythematosus is a generalized subepidermal blistering skin eruption in patients suffering from systemic lupus erythematosus. Type VII collagen was initially identified as the target antigen.Observation
We studied an unusual patient who had bullous systemic lupus erythematosus. The patient fulfilled the criteria of systemic lupus with an antinuclear antibody titer of 1:5120. Immunopathological testing revealed in vivo deposition of all IgG subclasses, secretory IgA1, and both light chains at the patient's skin basement membrane. The in vivo-bound IgG and IgA were localized at the hemidesmosomes and lamina densa. The patient's IgG and IgA circulating autoantibodies labeled both the epidermal roof and the dermal floor of salt-split skin and recognized the hemidesmosomal protein BP230 as well as the full-length native form and the recombinant noncollagenous domain 1 of type VII collagen (anchoring fibril). In addition, the patient's IgG autoantibodies recognized the anchoring filament proteins laminin-5 and laminin-6 (alpha3 chain and gamma2 chain).Conclusions
We conclude that patients with bullous systemic lupus erythematosus may have autoantibodies to multiple basement membrane components critical for epidermal-dermal junctional adhesion. Possible pathogenic mechanisms in this patient's clinical diseases include provocation of organ-specific disease (bullous disease) by systemic autoimmunity (lupus) and the "epitope spreading" immune phenomenon.