Survival after transfusion of Rh-positive erythrocytes previously incubated with Rh antibody.

It has been concluded that if blood is taken from a patient with acquired haemolytic anaemia and transfused to a normal recipient the erythrocytes survive normally (Loutit and Mollison, 1946). This finding is not an easy one to understand since the erythrocytes at the moment of transfusion are coated with antibody and give a positive direct Coombs test, and it might be thought that if the degree of sensitization were adequate only the addition of complement was necessary to complete their lysis. In discussing this finding it was suggested that immune body might be washed off the erythrocytes when they were put into the circulation of a normal patient. It was further suggested that there was probably some other substance, " co-haemolysin," present in the plasma of patients with acquired haemolytic anaemia in addition to the antibody giving the positive Coombs reaction. Some such theory was necessary to explain the findings in the case of a patient who recovered spontaneously from acquired haemolytic anaemia and no longer destroyed transfused erythrocytes rapidly although her own red cells continued to give a positive direct Coombs test. Owren (1947) made some observations which were a little at variance with those reported above. He took erythrocytes from a patient with acquired haemolytic anaemia and transfused them to a normal-recipient. Approximately 50 per cent of the erythrocytes disappeared from the recipient's circulation within three days, and during this period it could be demonstrated that the surviving donor cells gave a positive direct' Coombs test. After three days the surviving cells no longer gave a