Levels of complement factor C3 and its activated product, C3a, in operatively salvaged blood

In intra-operative blood salvage the collected blood is exposed to traumatized tissue and a synthetic circuit. Because of this exposure it was expected that the complement system, which is a contact system present in plasma, would be activated in salvaged blood. To determine whether this occurs, the plasma levels of the complement factor C3 and its activated fragment, C3a, were measured in intra-operative salvaged blood before and after washing. Samples were obtained from patients undergoing aortic surgery where intra-operative salvage was used. In the unwashed salvaged blood, the level of C3 fell (mean C3: 0.33 g/L) and the level of C3a increased (mean C3a: 1994 ng/mL) compared with the patient circulating levels of C3 and C3a (mean C3: 0.70 g/L, mean C3a: 855 ng/mL) respectively. Washing of the collected blood reduced the C3a level (mean: 346 ng/mL) to the patient's level and reduced C3 to the lower detection limit of the test (less than 0.2 g/L). The raised level of C3a and the reduced level of C3 confirm that the complement system is activated and imply that other complement factors are also activated.