Background: The lupus band test (LBT) is an important auxiliary method in the diagnosis of systemic lupus erythematosus (SLE), but the mechanism of its formation is still unknown. There are many kinds of autoantibodies, such as basement membrane zone autoantibodies (BMZ-Abs), in patients with SLE.
Aim: To detect whether skin BMZ-Abs participated in the formation of the lupus band in SLE. Methods Immunoglobulin G (IgG)-type BMZ-Abs in 15 SLE patients were detected by means of immunofluorescence (IF), immunoblotting (IB), and immunoelectron microscopy (IEM).
Results: Direct immunofluorescence (DIF) on salt-split skin showed epidermal fluorescence in 12 of the 15 SLE patients. Two of the 12 patients also showed dermal fluorescence. Indirect immunofluorescence (IIF) on salt-split skin revealed that, in 12 of the 15 (80%) sera, antibodies were bound to the epidermal roof of the salt-split skin. IB showed that, in 14 SLE sera, autoantibodies reacted to 230, 200, 180, 130, and 97 kDa epidermal extracts and 75 kDa dermal extracts. Direct (DIEM) and indirect (IIEM) immunoelectron microscopy showed that gold particles were directed to every region of the BMZ, including hemidesmosomes, lamina lucida, lamina densa, and sublamina densa.
Conclusions: BMZ-Abs in SLE sera may participate in the formation of the lupus band.