Acquired Hemolytic Anemia I. the Relation of Erythrocyte

I T IS NOW evident that the syndrome of acquired hemolytic anemia represents a distinct entity which is separate in pathogenesis and course from the commonly described familial hemolytic jaundice. This distinction, which was recognized by the writers of the early part of the century, was lost sight of by many more recent observers, who suggested that acquired hemolytic anemia was simply a sudden outcropping of a latent inborn defect. Since spherocytosis of the red cells is always present in congenital hemolytic jaundice and is sometimes observed in acquired hemolytic anemia, the confusion was natural, particularly when a sharp distinction could not always be made on clinical grounds. Beginning with the red cell survival experiments of Dacie and Mollison,’ it has become increasingly evident that acquired hemolytic anemia is caused by a “hemolysin’ ‘ ‘ active for all erythrocytes, while congenital hemolytic jaundice is due to a defect in red cell structure.’ During the last few years it has been possible to demonstrate sensitization of erythrocytes from patients with acquired hemolytic anemia with immunologic technics developed in the field of Rh sensitization.37 We have some evidence, then, by analogy, that the hemolytic agent in acquired hemolytic anemia is an immune body similar to the univalent or hyperimmune Rh antibody and may be a response to antigenic stimulus. The ready demonstration of the abnormal immune mechanism in acquired hemolytic anemia elevates this rather rare disease from the position of an obscure hematologic phenomenon of uncertain etiology to the general field of abnormal immunology. Because of the unique properties of erythrocytes, the affected tissue can be isolated and subjected to close observations so that variations in the rate of production of the hemolysin can be measured in relation to severity of the disease and to any type of therapeutic procedure. It is worthwhile at this point to summarize our knowledge of the antibodylike agent which appears to he responsible for the destruction of red cells in acquired hemolytic anemia. i. The destructive agent appears to be a fraction of plasma protein, probably a globulin, since erythrocytes from persons with acquired hemolytic anemia are agglutinated with the anti-human serum rabbit serum of Coombs, Mourant and Race,3 as are cells sensitized by Rh hyperimmune antibody. Red cells from normal individuals and from patients with other types of disease are not agglutinated by this reagent.