Does the complement system become activated while platelet concentrates are stored at room temperature?

Details

Platelet activation during preparation and/or room-temperature storage of platelet concentrates in plastic containers had been recognized. Many biological causes had been proposed. Activated complement, a multi-enzyme system, was considered one possible source of molecules that could lead to platelet activation.

In this laboratory storage study, researchers investigated functional complement activity and the generation of complement-derived ligands in the supernatant plasma of platelet concentrates over 5 days at room temperature. They used hemolytic tests of functional classical and alternative complement pathway activity, along with a kinetic test for complement-mediated inhibition of immune complex precipitation. They investigated C3 activation products (C3, C3c, C3dg) in plasma using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting, and on platelets using immunofluorescence.

Complement activation was evident during storage, and C3c and C3d fragments were clearly demonstrated in plasma. The amount of C3d fragments on platelets gradually increased during the first 3 days of storage. At the end of 5 days, the platelets were C3d negative. The authors proposed two possible mechanisms for C3d disappearance: shedding and/or further degradation of C3d fragments.

The findings indicated that complement activation and the generation of complement-dependent ligand–receptor interactions may be mechanisms of platelet activation in concentrates stored at room temperature.