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.