[The role of the liver in the intestinal immune system. Origin of specific B-lymphocytes in the liver following intestinal immunization].

After intestinal priming with cholera toxin (CT) the highest number of specific B-cells is found in the liver, whereas after an intestinal booster dose of CT, high numbers of specific B-cells also locate to the intestine. Correspondingly, after priming, 70% of biliary IgA anti-CT are synthesized within the liver and after boosting approximately 30%. To test the hypothesis that the B-cells in the liver are derived from intestinal lymphoid tissue, thoracic duct lymphocytes (TDL) from intestinally primed and boosted donor rats were transferred to syngeneic recipients. TDL from primed donors predominantly homed to the liver of recipients, and TDL from boosted donors in high numbers to the intestine also. High biliary IgA anti-CT titers in both groups of recipients proved that the immune response was transmitted successfully. In the rat, at any rate, the liver is part of the intestinal immune system not only in terms of IgA transport but also as a specific homing organ for intestinal B-cells.