Immunoglobulin kappa light chain, apolipoprotein E, albumin, apolipoprotein A-I, antithrombin-III, α1-antitrypsin, serotransferrin, immunoglobulin heavy constant mu, immunoglobulin J chain, complement C4-A, and complement C3 were significantly increased in bile of CCA patients comparing with control patients. The gene discussed is C4A; the disease is cholangiocarcinoma.