Abstract
In vitro interaction between monocytes and complement-coated erythrocytes from two patients with immune hemolytic anemia was studied serially before and after corticosteroid treatment. Erythrocytes from one patient were coated with IgA warm antibodies and complement (C3), and bound to monocytes as rosette fashion in Hanks' solution, but were not phagocytized by monocytes. Erythrocytes from another patient who developed hemolytic anemia after taking Methyldopa were coated with IgG warm antibodies and C3, and were readily phagocytized by monocytes. Rosette formation of the erythrocytes of the former patient was completely inhibited by the addition of 0.01 M EDTA, but not inhibited by the addition of IgG (10 μg/ml) in the medium. Phagocytosis of the erythrocytes of the latter patient was completely inhibited by the addition of IgG and moderately inhibited by the addition of EDTA. Thus, it was suggested that the binding of the erythrocytes of the former patient was mediated via C3 receptors of monocytes and the phagocytosis of the erythrocytes of the latter patient was mediated via both Fc and C3 receptors. After prednisolone (PSL) administration, in vivo hemolysis improved in parallel to the decrease in C3 Coombs' titers of erythrocytes and in vitro C3 receptor-mediated binding of erythrocytes to monocytes. PSL treatment did not reduce significantly IgG Coombs' titers and in vitro IgG receptor-mediated phagocytosis of patient's erythrocytes. In vitro erythrophagocytosis via C3 receptor was not parallel to the in vivo hemolysis. PSL treatment rapidly reduced C3 on the sensitized erythrocytes and the inhibition of the C3 receptor mediated interaction between mononuclear phagocytes and erythrocytes seems to be an important mechanism of PSL induced remission of hemolysis.
