The use of radioactive isotopes in immunological investigations. 13. The role of leucocytes and nonplasma antibody in the removal of antigenic proteins from the blood stream of immunized rabbits.

Abstract

Bovine plasma albumin and horse serum labeled with iodne-131 were employed in studies on the behavior and elimination of intravenously injected native proteins in normal and immune rabbits. Actively, but not passively, immunized rabbits can eliminate rapidly from their blood more antigen than their sera can precipitate in vitro, except when they have been in the immune state for a long time. When immune rabbits are given an injection of antigen sufficient to react with all the antibody in their plasma, a second small injection of antigen is eliminated from the blood more rapidly than a similar dose injected into normal rabbits. There is evidence for deposition of part of the second injected dose in the liver, lungs, and spleen of the immune rabbits. The significance of these observations is discussed and it is concluded that some non-plasma antibody is partly responsible for the immune responses observed when an antigen is injected into specifically immunized rabbits. This non-plasma antibody is unlikely to be mainly in the lymphocytes or lymphoid tissue. Injection of antigen into immune, but not into normal, rabbits causes a profound leukopenia, which is due to a fall in the numbers of both lymphocytes and granulocytes. This phenomenonmore » is not modified by the prior injection of cortisone in amounts sufficient to cause a lymphocytopenia.« less