The Metabolism of Some Antigen-Antibody Complexes in the Rabbit

Abstract

Rabbits sensitized to beef gamma globulin (BGG) and normal controls were injected intravenously with small amounts of insoluble, suspended complexes formed in vitro between I¹³¹-trace labeled BGG (I¹³¹-BGG) and its homologous rabbit antibody. At intervals animals were sacrificed and the protein bound activity was determined in their blood and organs. It has been shown that the clearance from the blood proceeds more rapidly in sensitized than in control animals because the antibody in their serum reduces dissociation of complex. The organ distribution pattern is similar in both sensitized rabbits and controls and it thus appears that elimination of complex from blood does not depend on any sensitization of tissues. The spleen, shortly after injection, has the highest specific activity of any organ. Because of their size the liver and lungs account for the greatest removal of injected activity from the circulation. In sensitized animals injected with labeled antigen (i.e. in tracing complex formed in vivo) the spleen and lymph nodes have the highest specific activities of any organ; whereas in normal animals these activities are quite low. Thermally denatured I¹³¹-BGG, when injected intravenously, is eliminated from blood at rates comparable to antigen-antibody complex in sensitized rabbits, but is excreted more rapidly from the organism. A difference in the rate of degradation and elimination of native insoluble protein (antigen-antibody complex) and denatured insoluble protein is indicated.