Evidence that anti-basement membrane zone antibodies in bullous eruption of systemic lupus erythematosus recognize epidermolysis bullosa acquisita autoantigen.

Circulating and tissue-deposited IgG antibodies to the cutaneous basement membrane zone (BMZ) were detected in 3 patients with the clinical, pathologic, and immunologic features of bullous eruption of systemic lupus erythematosus (SLE). The antibodies were present in sera and IgG fractions in all cases and in eluates of cutaneous immune deposits from one of the cases. The antibodies were easily detected in sera by indirect immunofluorescence on adult human thigh skin separated through the lamina lucida by incubation in 1.0 M NaCl but were less easily detected on intact neonatal foreskin. The antibodies had features of epidermolysis bullosa acquisita (EBA) anti-BMZ antibodies including binding to the dermal side of the BMZ in separated skin, binding to the cutaneous but not vascular or glomerular basement membranes, binding to and just below the lamina densa, and binding to 290 or 290 and 145 kD dermal proteins previously identified as components of the EBA autoantigen. The antibodies were relatively specific for SLE patients with features of bullous eruption of SLE since they were detected in 3 of 4 of those cases and in only 1 of 20 SLE patients without blisters. These results show anti-BMZ antibodies with features of EBA antibodies are present in patients with bullous eruption of SLE and suggest there may be a close relationship between that disease and EBA. The results also suggest that EBA antibodies may be part of the autoantibody spectrum of SLE and that separated skin is more sensitive than intact skin for their detection.