EFFECT OF C3B INACTIVATOR ON MONOCYTE-BOUND C3-COATED HUMAN ERYTHROCYTES

  • 1 January 1978
    • journal article
    • research article
    • Vol. 52  (5) , 896-904
Abstract
As a model of Ig[immunoglobulin]M-induced hemolytic anemia in man, human erythrocytes were sensitized with IgM antibody and coated with complement [C] components, including C3 and C4, using human serum as a source of C. These coated red cells were interacted with monolayers of human mononuclear phagocytic cells (monocytes). C-coated red cells so bound could be displaced from their monocyte attachment site in a dose- and time-dependent manner by serum factors, including C3b inactivator (C3blNA). These factors were more efficient in inactivating red cell-bound C components prior to interaction of the coated cells with monocytes. With large amounts of C per erythrocyte, measured as membrane-bound C3, the ability of the serum inactivating factor(s) to remove the C-coated red cells from the monocyte surface was compromised and persistently bound red cells were progressively phagocytosed. These studies implicate C3blNA in the displacement of C-coated erythrocytes, formed from the interaction of IgM antibody and serum C, from the hepatic macrophage in IgM-induced immune hemolysis. The concentration of C components, especially on the erythrocyte surface, and the level of C3blNA and perhaps other inactivators may be important features regulating hemolysis in this disorder.