Autoantibody profile of a cohort of 54 Italian patients with linear IgA bullous dermatosis: LAD-1 denoted as a major auto-antigen of the lamina lucida subtype

Abstract

Linear immunoglobulin A (IgA) bullous dermatosis (LABD) is characterized by the presence of multiple IgA autoantibodies, and a comparatively lesser number of IgG antibodies, directed against different hemi-desmosomal antigens. The main autoantigens are LAD-1, LABD-97, BP180 and BP230, type VII collagen and laminin 332. The serology of 54 Italian patients with LABD was studied retrospectively using enzyme-linked immunosorbent assay (ELISA), immunoblotting assay, and indirect immunofluorescence on monkey oesophagus and salt-split skin. Among these, indirect immunofluorescence of salt-split skin elicits the grea-test sensitivity. Sixty-three percent of the sera were observed to be positive, with a lamina lucida pattern observed in 48%, a sub-lamina densa pattern in 2% and a mixed pattern in 13% of cases. IgA reactivity to LAD-1 on immunoblotting was found in 52% of sera, to BP180-NC16A by ELISA in 32% and to BP230 in 26%. Only 17% of patients had circulating IgG autoantibo-dies. LAD-1 was determined to be a major autoantigen of the lamina lucida subtype. Combined serological as-says demonstrated a high sensitivity (82%), sugges-ting that this approach could support diagnosis when a biopsy is not feasible or direct immunofluorescence results are negative.