Haemolytic anaemia in the rabbit following the injection of human anti-I cold agglutinins.

Anti-I cold agglutinins, purified from the serum of patients with chronic cold haemagglutinin disease, were injected intravenously into adult rabbits, which are known to have I antigen on their red cells. This caused acute intravascular haemolysis, with haemoglobinaemia, haemoglobinuria and anaemia. In addition, there was an acute, but usually transient, thrombocytopenia and neutropenia. Anticoagulation with heparin or Arvin had no influence on the effects of cold agglutinin injection, but massive doses of heparin, thought to interfere with complement binding by the cold agglutinin, did prevent the haemolysis, thrombocytopenia and neutropenia. A rabbit, given daily injections of cold agglutinin, developed significant intravascular haemolysis only with the first injection. However, a chronic extravascular haemolytic anaemia occurred with marked spherocytosis, reticulocytosis and shortening of the red cell survival. The effects of injection of human anti-I cold agglutinins into rabbits are analogous to certain aspects of the human disease and this rabbit model may be useful in further studies of in-vivo complement binding and removal of complement coated cells.