A homeostatic mechanism for the removal of antigen from the portal circulation.

Immunogenic molecules are being absorbed continually from the alimentary tract and a substantial proportion of normal people have detectable levels of circulating antibody against soluble food proteins and intestinal bacteria. In our view antibodies to soluble proteins form part of a physiological mechanism for preventing these proteins from entering the systemic circulation. In the absence of antibody the liver failed to remove significant quantities of soluble protein antigen from the portal circulation, but in the animal with sufficient circulating antibody to combine with antigen in optimal proportions, the liver retained 80 per cent of the injected protein. The liver became progressively less efficient for the removal of injected complexes which had been prepared and contained increasing amounts of antigen in excess of optimal proportions. The consequences of antigen excess, as they relate to inflammatory bowel disease, are discussed. The theoretical consequences of antibody excess are also discussed.