Complement activation during cardiopulmonary bypass.

Conversion of C3, the third component of complement, has been studied using a two-dimensional immunoelectrophoretic method. Evidence of C3 conversion has been obtained in stored donor blood, in patients during and after cardiac surgery involving cardiopulmonary bypass, and occasionally during thoractomy for pulmonary resection. It is suggested that complement activation is one factor contributing to tissue injury after cardiopulmonary bypass.