Hemolysins in acquired hemolytic anemia; effect of pH on the activity in vitro of a serum hemolysin.

By J. V. DAdE, M.B., M.R.C.P. LONDON H YDROGEN ion concentration has a controlling effect upon many hemolytic systems, both simple and complex. Osbor& in 1934 reviewed the early literature on the effect of pH on the hemolysis by complement of corpuscles sensitized by hemolytic immune body. He found that the optimum reaction for the hemolysis of sheep corpuscles by guinea pig serum was about pH 7.5 with inhibition below pH and above pH 9.7. More recently, Seifter et al.2 have reported unimpaired activity of human complement between pH 6.i and 8.4 and irreversible and rapid destruction below pH 4.2. and above pH io. i. The effect of pH or carbon dioxide concentration on the activity in vitro of hemolytic antibodies of human origin has seldom been considered except in the case of chronic hemolytic anemia with nocturnal hemoglobinuria (Ham,3 Dacie and Richardson4), in cold hemoglobinuria where the adjuvant effect of carbon dioxide on hemolysis has been sometimes referred to (Van den Bergh,’ Hannema and Rytma,6 Wagley, Zinkham and Siebens7) and in a case of acute hemolytic anemia in infancy reported by David and Minot.8 In the present communication are reported observations on the activity in vitro of an abnormal hemolysin in the serum of a patient with idiopathic acquired hemolytic anemia, and the effect of pH on its action. It was found that although little or no hemolysis resulted when normal Group 0 corpuscles were suspended in unacidified patient’s serum (pH 8.o), hemolysis readily took place if the pH of the serum-corpuscle suspension was adjusted to an optimum (pH 6.8 to 7.0) by the addition of suitable volumes of acid. If graded amounts of acid were added to serum it could be shown that the range of pH within which hemolysis could be observed corresponded quite closely to that found in chronic hemolytic anemia with nocturnal hemoglobinuria (Dacie and Richardson4). In the final section of this paper, these observations are contrasted with the pH ranges for the hemolysis by complement of erythrocytes sensitized by anti-A or anti-B isohemolysin and of group 0 erythrocytes sensitized by a “cold” hemolysin present in the serum of a patient with cold hemoglobinuria.