IGHG3 and Autoimmunity: Although we have already hypothesized a possible role of IgG3 in the pathogenesis of primary biliary cirrhosis (PBC) [9] or mixed cryoglobulinemia (MC) [28], strengthening the hypothesis of a pathogenic role of IgG3 in liver-related autoimmunity, to date there are no studies in the literature about the possible role of IgG3 in initiation or progression of ILD in SSc patients.