Each of 4 dogs was given two successive transfusions of incompatible dog erythrocytes at intervals of ninety or one hundred and twenty minutes. Measurements were made of the concentration of hemoglobin, complement and isoantibody in the plasma or serum of the recipients and of the rate of disappearance of the donated cells labeled with radioactive iron.
In each experiment the donated red corpuscles were destroyed much more slowly after the second transfusion than after the first, and the hemoglobinemia produced by the first transfusion was not appreciably augmented by the second transfusion. The successive transfusions at short intervals were considered nearly equivalent to single large transfusions but permitted separate study of the effects produced.
The rate of hemolysis was influenced by the initial titers of both antibody and complement. In dogs with high antibody titer, available complement appeared to limit the rate of destruction of incompatible donated cells. In the presence of adequate complement the rate of hemolysis was limited by the disappearance of antibody when the initial titer of antibody was low.
Limitation of the degree of hemoglobinemia due to limitation of the rate of destruction of transfused incompatible erythrocytes and the rather efficient clearance of plasma hemoglobin explains in part the failure of some hemolytic transfusion reactions to produce severe or fatal renal damage.
It is emphasized that most investigations of hemoglobinuric nephrosis in animals have dealt with the injection of hemoglobin solutions which resulted in hemoglobinemia of much greater intensity than it has been possible to produce by transfusion of large volumes of incompatible red corpuscles.