Detection of autoantibodies against alpha-2-macroglobulin-like 1 in paraneoplastic pemphigus sera utilizing novel green fluorescent protein-based immunoassays

•The majority of PNP patients develop autoantibodies against A2ML1.•The biological function of A2ML1 in the epidermis remains incompletely understood.•Current diagnostic methods in PNP are inadequate to detect anti-A2ML1 antibodies.•Here we developed sensitive and quantitative assays to detect anti-A2ML1 antibodies.•Our approach can be applied for the characterization of antibodies against various antigens.