PDCD1 and viral hepatitis: 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).