The influence of EDTA Vacutainer blood collection tube on the level of blood interleukin-1 receptor antagonist.

BACKGROUND: The use of anticoagulants may influence the composition of blood cells and interfere with plasma levels of IL-1ra when unprocessed EDTA blood samples are stored for long periods of time. METHODS: Blood was drawn into EDTA and heparinized blood collection tubes from 11 HIV-1 negative men participating in the Multicenter AIDS Cohort Study (MACS) and 4 healthy volunteers. The blood was processed according to the experiments detailed in the method and after incubation; supernatants were collected and stored at -70 °C until batch testing using IL-1ra ELISA. RESULTS: There was no difference between the levels of IL-1ra in EDTA blood collected into plastic and glass tubes (p = .911). There were significant increases from baseline levels of IL-1ra (p ≤ .05) after 24 h incubation for diluted whole blood and PBMC supernatants but not for granulocytes supernatants. CONCLUSION: EDTA as an anticoagulant influences the blood concentrations of IL-1ra in unprocessed blood. Thus, EDTA blood is not a suitable specimen for measurement of IL-1ra. Other types of anticoagulated blood should be processed within one hour of draw whenever measuring plasma levels of IL-1ra.