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
Emanuele Cozzani, Giovanni Di Zenzo, Giulia Gasparini, Adele Salemme, Arianna Fay Agnoletti, Camilla Vassallo, Marzia Caproni, Emiliano Antiga, Angelo V. Marzano, Riccardo Cavalli, Corrado Ocella, Clara De Simone, Aurora Parodi
Linear IgA bullous dermatosis (LABD) is characterized by presence of multiple IgA autoantibodies, and a comparatively lesser number of IgG antibodies, directed against different hemidesmosomal antigens. The main autoantigens are LAD-1, LABD-97, BP180 and BP230, type VII collagen and laminin 332. We retrospectively studied the serology of 54 Italian patients with LABD 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 greatest 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 the 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 possessed circulating IgG autoantibodies. LAD-1 was determined to be a major autoantigen of the lamina lucida subtype. Combined serological assays demonstrated a high sensitivity (82%), suggesting that this approach could support diagnosis when a biopsy is not feasible or direct immunofluorescence results are negative.
Linear IgA bullous dermatosis is a rare autoimmune disease, marked by blistering, affecting both children and adults. It is characterized by auto-antibodies targeting various types of skin proteins. We retrospectively studied 54 Italian patients with this disease. The auto-antibody targets were investigated using various blood tests (enzyme-linked immunosorbent assay, immunoblotting and indirect immunofluorescence on monkey oesophagus and salt-split skin). Indirect immunofluorescence on salt-split skin elicited the greatest diagnostic sensitivity. The most common target was LAD-1, followed by BP180-NC16A and BP230. Eighty-two percent of patients possessed circulating IgAs and only 15% possessed circulating IgG auto-antibodies. Combined serological tests supported the diagnosis of linear IgA bullous disease.