Experiences with citrate rather than heparin as an anticoagulant for ¹⁸F-FDG labeling of leukocytes

In all reported clinical studies with (18)F-FDG-labeled leukocytes, heparin was used as an anticoagulant during labeling. Theoretically, the substitution of heparin with citrate should be advantageous.

Blood from healthy controls was sampled in duplicate, anticoagulated with citrate or heparin, and labeled with (18)F-FDG, and the labeling yield was measured. Viability was checked with the trypan blue exclusion technique. Moreover, 4 in vivo PET/CT studies were performed after the reinjection of leukocytes labeled after citrate anticoagulation.

The labeling yields obtained with citrate and heparin were not significantly different (P = 0.447). Viability was greater than or equal to 99%. The quality of the PET/CT studies was excellent. In the in vivo studies, the mean labeling yield was 78%-better than or equal to that reported with heparin as an anticoagulant.

Citrate is at least as effective as heparin as an anticoagulant, does not (unlike heparin) increase granulocyte activation, and should be the preferred anticoagulant for (18)F-FDG labeling of leukocytes.