CD8A and primary biliary cholangitis: For example, in PBC, monocytes are more sensitive to toll-like receptor signalling7; portal infiltrates consist mainly of CD4+ T cells, heavily skewed towards TH1 and TH17 cells8,9; there is insufficiency of TREG cells10; CD8+ T cells infiltrate the biliary epithelia and cause segmental apoptotic destruction of cholangiocytes11,12; and B cells contribute to disease through cross-presentation of antigen and production of autoantibodies.13,14