THE MECHANISM OF HEMOLYSIS IN PAROXYSMAL COLD HEMOGLOBINURIA. I. THE ROLE OF COMPLEMENT AND ITS COMPONENTS IN THE DONATH-LANDSTEINER REACTION 12

Abstract

Studies of sera from 2 patients with paroxysmal cold hemoglobinuria (PCH) have shown that large amts. of complement may be necessary for hemolysis in the Donath-Landsteiner reaction. By using an adequate amt. of complement, the hemolysins from both patients were found to be stable at 62[degree]C. An excess of complement is necessary for antibody titration, since a reciprocal relationship exists between the amt. of complement present and the antibody titer. Agglutination by antiglobulin serum of erythrocytes sensitized in dilutions of PCH serum provides another measure of antibody level, the titers obtained being comparable to those found by hemolysin titration in the Donath-Landsteiner reaction. Complement is essential in both the cold and warm phases of this reaction, and there is a reciprocal relationship between the amts. of intact complement required in these 2 phases. The erythrocyte-PCH antibody system is unique in that it requires complement for antibody fixation as well as for subsequent hemolysis. The PCH hemolytic system is unusual in another respect, because all components of complement are not necessary for hemolysis. Hemolysis occurs inthe absence of C''1 and C''3. Hemolysis does not occur when C''4 is missing in the cold phase, or when C''2 is missing in the warm phase. Since only 2 components of complement are required for hemolysis in PCH, titration of complement in a serum by the sheep cell-amboceptor system, which requires all 4 components, may not measure the capacity of that serum to produce hemolysis with PCH antibody.