In 2014, a study investigated the presence of anti-PD-1 antibodies, measured by indirect enzyme-linked immunosorbent assay, in sera of 52 type 1 AIH patients, 24 patients with drug-induced liver injury (DILI), 30 patients with acute viral hepatitis (AVH), 11 patients with primary sclerosing cholangitis (PSC), and 62 healthy volunteers (53). This evidence concerns the gene PDCD1 and sclerosing cholangitis.