Anti-laminin 332 antibody detection using biochip immunofluorescence microscopy in a real-life cohort of Italian patients with mucous membrane pemphigoid

Mucous membrane pemphigoid (MMP) with anti-laminin 332 autoantibodies may be associated with malignancies, however, current serological assays have considerable limitations. At present, no commercial test for anti-laminin 332 antibodies is available, restricting the diagnosis to specialized laboratories worldwide. Biochip immunofluorescence microscopy has shown promising results in selected cohorts of laminin 332-MMP patients. Objectives: To detect anti-laminin 332 antibodies by biochip immunofluorescence microscopy in a real-life cohort of MMP patients and compare the results with those from traditional immunoblotting. Sera were obtained from 31 patients with MMP, 28 with bullous pemphigoid, five with pemphigus vulgaris, five with paraneoplastic pemphigus, five with linear IgA bullous dermatosis, and 10 controls, and analysed by biochip immunofluorescence using human cells expressing laminin 332. Immunoblotting was performed using purified laminin 332. MMP involved the oral mucosa in 65%, ocular mucosa in 9%, oral and ocular mucosae extensively in 13% as well as other mucosae in 13% of patients. Concomitant cutaneous involvement was reported in 35% of patients. Three MMP patients had an underlying malignancy. Anti-laminin 332 antibodies were detected in 2/31 (6%) cases by both methods. Based on immunoblotting, both laminin 332-positive sera reacted with α3 chain (in one case also with β3 chain). Both patients with anti-laminin 332 antibodies had extensive mucosal involvement and only one had cancer. Anti-laminin 332 antibodies were not detected in control groups. Biochip immunofluorescence is an appropriate technique to detect anti-laminin 332 antibodies which should be tested in patients with MMP.