Lysis by Anti‐I in Dyserythropoietic Anaemias: Role of Increased Uptake of Antibody

Summary. Antibody lysis has been studied in PNH, in congenital dyserythropoietic anaemia and in other blood diseases with abnormal erythropoiesis. This last group of acquired dyserythropoietic anaemias included, especially, aplastic anaemia, megaloblastic anaemias, myelosclerosis and leukaemia. Cold‐antibody lysis, complement sensitivity and anti‐I antibody uptake by red cells were measured. In both congenital dyserythropoietic anaemia and the acquired dyserythropoietic anaemias of all types there was increased cold‐antibody lysis which was mainly or entirely due to increased antibody binding, without increased complement sensitivity. In PNH, on the other hand, there was slightly increased antibody uptake but lysis was much greater than could be accounted for by this alone and was mainly due to increased complement sensitivity. PNH thus appears to be uniquely different from the dyserythropoietic anaemias. Also, whereas in PNH complement sensitivity curves indicated the presence of two populations of red cells, in the dyserythropoietic anaemias the curves suggested that only one cell population was present.