EFFECT OF HEPARIN ON COMPLEMENT ACTIVATION AND LYSIS OF PAROXYSMAL NOCTURNAL HEMOGLOBINURIA (PNH) RED-CELLS

  • 1 January 1977
    • journal article
    • research article
    • Vol. 50  (2) , 239-247
Abstract
The effect of heparin upon the binding of the 3rd component of complement (C3) to PNH [paroxysmal nocturnal hemoglobinura] in vitro and their subsequent hemolysis is described. Heparin, in increasing concentrations, progressively inhibits membrane C3 fixation and hemolysis when the classic complement pathway is activated by anti-red cell antibodies. Heparin has a biphasic effect upon membrane C3 fixation and hemolysis when complement is activated in serum at decreased ionic strength (sucrose lysis) or in serum at decreased pH (Ham test). Heparin in concentrations above 2 U[units]/ml inhibits C3 binding and hemolysis; lower concentrations of heparin enhance the consequences of complement activation by these 2 procedures. This enhanced complement activation may explain the increased hemolysis sometimes reported in PNH patients treated with heparin and suggests that heparin may aggravate the consequences of pathologic alternative pathway complement activation in other diseases.