CA4 and autoimmune pancreatitis: However, the autoimmunity theory is not abandoned because it is known that carbonic anhydrases (Cas), lactoferrin (LF), a red iron-binding protein, are mainly present in the secretion of body fluids such as pancreatic juice and that anti-LF and anti-CA II, anti-CA I, and anti-CA II, and anti-CA IV are common nonspecific autoantibodies found in patients with AIP, but the role of these autoantibodies in the pathogenesis of AIP is still unclear.