CA5B and immunoglobulin G4-related sclerosing disease: Autoantibodies against carboanhydrase 2 (CA2) and 4 (CA4) have early been described in AIP and IgG4-RD.1, 69In human cholangiocytes, expression of CA2, CA5b, CA9 and CA12 is identified.85Subsets of IRC and PSC patients have anti-CA2 and anti-CA5b autoantibodies that functionally inhibit human recombinant CA isoforms, thereby potentially rendering human cholangiocytes more susceptible to bile acid-induced damage.85Additional data are upcoming to further substantiate these potentially relevant findings.