Autoantibody detection by conventional and novel mosaic BIOCHIP technique: A comparative analysis for the diagnosis of autoimmune bullous diseases

Background Circulating autoantibodies in patients with autoimmune bullous diseases can be detected by indirect immunofluorescence (IIF) microscopy. The sensitivity of this method depends on the substrate used. Normal human skin (NHS) and salt-split skin (SSS) are widely used in conventional serodiagnosis of autoimmune bullous diseases. A novel mosaic biochip has been reported to be a highly sensitive and specific test to detect the circulating antibodies in this subset of patients. Objectives This study was designed to compare IIF microscopy by conventional and mosaic biochip technologies in the serodiagnosis of patients with autoimmune bullous diseases. Methods This cross-sectional study included sera of 103 patients with autoimmune bullous diseases. Conventional IIF microscopy was carried out using NHS and SSS substrates. IIF using the mosaic biochip was performed as per the manufacturer's instructions. Results The conventional technique detected intercellular staining with IgG in 62 patients, and the mosaic biochip detected it in 56 monkey oesophageal samples. The latter also detected both desmoglein (Dsg) 1 and 3 in 45 patients and Dsg 1 and 3 individually in eight and ten serum samples, respectively. Both techniques detected epidermal staining in the SSS of 37 patients with sub-epidermal autoimmune bullous diseases, and dermal staining was observed in seven sera. Seventeen patients with epidermal staining patterns revealed antibodies to BP180 only; six patients showed reactivity to both BP 180 and 230. Limitation Due to financial constraints, sera of healthy controls could not be studied. Conclusions The BIOCHIP mosaic IIF is an useful adjunct IIF technique. It not only helps to detect the staining pattern but also identify the target antigens in common autoimmune bullous disease. Sensitivity of conventional IIF in detecting ICS is 93.9% in contrast to 84.4% with the BIOCHIP mosaic technique. However, mosaic BIOCHIP technique helped to identify the target antigens in common AIBD.