STUDIES ON IMMUNE HUMAN HEMOLYSIS

Abstract

C[image]1 is the only component of complement required in the initial cold phase of the Donath-Landsteiner reaction and initiates the hemolytic process. The other components react in the subsequent warm phase to cause hemolysis. C[image]1-esterase completes the cold phase in the absence of other components; its effect is blocked or reversed by serum inhibitor of C[image]1-esterase. The sequence of action of the components is C[image]l, C[image]4, C[image]2 and C[image]3. The reaction with C[image]1 requires Ca++, that with C[image]2 requires Mg++. The data support the hypothesis that complement action is initiated by the enzymatic properties of C[image]1.