TNF and autoimmune hepatitis: pIgR mediates transport of pIg (in particular dimeric IgA) into external secretions, which provide the first line of adaptive immune defense against ingested, inhaled, and sexually transmitted pathogens.23 The key regulator of pIgR expression is cytokines, such as INF‐γ, TNF, and IL‐1.24 In comparison with the control group, pIgR increased to 2.7 times in AIH and lowered to 1.66 times in AIC.