CD4 and primary biliary cholangitis: In PBC pathogenesis, liver macrophages are activated by CD4 and CD8 lymphocytes stimulated by the pyruvate dehydrogenase complex (PDC-E2), which is the autoantigen targeted by AMAs.3–5 The activated macrophages produce a proinflammatory response through the activation of cytotoxic T cells as well as Th1-positive and Th17-positive T cells producing interferon-γ and TNF-α.