Role of the liver in the rat intestinal s-IgA system.

Rat bile is an important source of s-IgA and FSC about 10 mg of s-IgA are poured daily in the duodenum via the bile. The normal rat liver is capable of actively transferring IgA from the circulation into bile against a strong concentration gradient. Circulating IgA transferred in bile was bound to SC. Ligature of the rat bile duct induces a large and selective increase of the IgA level in serum. All this additional IgA is s-IgA and even FSC appears in serum after bile duct obstruction. The liver appears to have an important reinforcing role in the intestinal s-IgA system of the rat.