Activation of the alternative pathway of human complement by haemoglobin

ABSTRACT

Haemoglobin solutions (concentration >1.5mg/ml), prepared from lysates of erythrocytes from a normal subject and from a patient with sickle cell anaemia, caused factor B and C3 cleavage and loss of haemolytic activity of factor B when incubated with fresh autologous serum. Under the same experimental conditions, preparations of erythrocyte stroma or of buffy coat lysates did not produce factor B and C3 cleavage. This reaction required Mg++ but not Clq or C4, indicating that the alternative complement pathway was activated (Summary)