Possible mechanism for in vitro complement activation in blood and plasma samples: Futhan/EDTA controls in vitro complement activation. Clin Chem 45

tion in citrate or EDTA plasma has prevented an accu-rate analysis of C-activation products generated in vivo. The aim of this study was to characterize handling and storage conditions required to prevent in vitro C activa-tion in blood and plasma samples collected with Fu-than/EDTA. Methods: BiotrakTM RIAs were used to quantitatively measure C3a and C4a in blood and/or plasma samples from healthy individuals (controls) and from liver trans-plant patients. Blood samples were routinely drawn into either EDTA (1 g/L) tubes or into tubes containing both EDTA (1 g/L) and Futhan (0.1 g/L) and immediately centrifuged at 2000g for 15 min at 4 °C. Results: In controls, C4a, but not C3a, in fresh samples (time 0) was higher in EDTA plasma than in Futhan