Bullous SLE: a phenotypically distinctive but immunologically heterogeneous bullous disorder.

Bullous systemic lupus erythematosus (SLE) is a rare blistering disease with a distinctive combination of clinical, histologic and immunopathologic features that together constitute a unique bullous disease phenotype. There appear to be at least two immunologically distinct subtypes of bullous SLE characterized by the presence or absence of circulating and/or tissue-bound basement membrane zone autoantibodies that recognize type VII collagen. The two subtypes are not clearly distinguishable except by indirect immunofluorescence and/or direct immunoelectron microscopy. In patients without circulating antibodies, immunoelectron microscopy is required to distinguish between the two subtypes. Patients with autoantibodies to type VII collagen are similar but not identical to patients with epidermolysis bullosa acquisita--another bullous disease associated with autoantibodies to type VII collagen. Autoantibodies to type VII collagen in patients with bullous SLE is only one of several lines of evidence that indicate autoimmunity to that protein and susceptibility to SLE are associated phenomena. In addition, there is emerging evidence for an association between epidermolysis bullous acquisita and SLE. There is also evidence that autoantibodies to type VII collagen are pathogenic in bullous SLE (and epidermolysis bullosa acquisita) and that their production is regulated by the class II major histocompatibility complex DR beta 1 allele, 1501 and possibly other DR beta 1 alleles that share a similar sequence of amino acids in the second hyper-variable region.