Human complement activation by polygeline and dextran 70.

The complement cascade is activated during cardiopulmonary bypass (CPB) and in trauma victims. In order to study whether plasma expanders may contribute to complement activation in these settings, fresh human serum was incubated with dextran 70 and polygeline. C3-activation products and the terminal complement complex (TCC) were quantified in enzyme immunoassays. At 37 degrees C, dextran caused immediate, dose-dependent C3 activation and TCC formation with decline later in the rate of TCC formation relative to serum-saline controls. High doses of polygeline caused slight activation after 15-30 min. The authors tested also the activation under conditions comparable to those found during clinical CPB. Activation induced by dextran and polygeline was increased by dilution of the serum. Furthermore, the plasma expanders counteracted the well-known inhibitory effects of heparin (4 IU/ml) and moderate hypothermia (30 degrees C) on complement activation. The authors conclude that dextran, and to a lesser extent polygeline, may contribute to complement activation during CPB and other clinical settings such as shock treatment.