An in vitro study to compare 99mTc-stannous colloids and 99mTc-HMPAO for labelling human leukocytes.
OBJECTIVE
Aim of the present study was to compare in vitro the labelling efficiency (LE) and cell viability (TBE) of autologous leukocytes labelled with (99m)Tc-SnF(2) and (99m)Tc-HMPAO, and to evaluate the quantity and quality of spontaneously released (99m)Tc (SR) from labelled cells at several time points after labelling.


METHODS
A total of 14 patients with different diseases and 18 normal subjects were included in this study. A blood sample was collected from each patient; purified autologous leukocytes were divided into 2 samples and labelled with (99m)Tc-SnF(2) and (99m)Tc-HMPAO. LE was evaluated at the end of labelling and TBE and SR were evaluated at 10 min and 1 h, 2 h and 4 h after labelling.


RESULTS
LE of (99m)Tc-SnF(2)-WBC was higher than (99m)Tc-HMPAO-WBC (61.2+/-18.7% and 43.3+/-11.3; p<0.0001) and we found an inverse correlation between blood glucose and labelling efficiency for both methods (p=0.02). Minimal differences were also observed between 2 methods after 10 min and 1 h, as far as the cell viability is concerned. The percentage of radioactivity spontaneously released from (99m)Tc-SnF(2)-WBC was significantly higher compared to (99m)Tc-HMPAO-WBC at each time point. Radioactivity released from labelled cells was predominantly (99m)Tc-SnF(2) and (99m)Tc-HMPAO with few free (99m)Tc (<20%).


CONCLUSIONS
Both radiopharmaceuticals are not toxic for WBC. Labelling with (99m)Tc-SnF(2) give a higher LE than with (99m)Tc-HMPAO; however, radiolabelled colloids are more released from labelled cells over a period of 4 h. While (99m)Tc-HMPAO is physiological excreted into gastrointestinal tract, (99m)Tc-SnF(2) can be re-uptaken in vivo by reticulo-endothelial cells of liver and spleen. These findings suggest that (99m)Tc-SnF(2)-WBC might be better than (99m)Tc-HMPAO-WBC for studying inflammatory bowel diseases.
Capriotti
G
G
Nuclear Medicine Unit, 2nd Faculty of Medicine, La Sapienza University, Rome, Italy.
D'Alessandria
C
C
Garin
E
E
Weber
E
E
Devillers
A
A
Lehmann
K
K
Corsetti
F
F
Lecloirec
J
J
Meller
J
J
Becker
W
W
Moisan
A
A
Signore
A
A
D002478:Cells, Cultured; D005260:Female; D006801:Humans; D007553:Isotope Labeling / Q000379:methods*; D007962:Leukocytes / Q000737:chemistry / Q000000981:diagnostic imaging* / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011874:Radiometry / Q000379:methods; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D017556:Technetium Compounds / Q000737:chemistry / Q000493:pharmacokinetics*; D019690:Technetium Tc 99m Exametazime / Q000737:chemistry / Q000493:pharmacokinetics* / Q000494:pharmacology*; D017971:Tin Compounds / Q000737:chemistry / Q000493:pharmacokinetics*
D019275:Radiopharmaceuticals; D017556:Technetium Compounds; D017971:Tin Compounds; C033493:technetium Tc 99m tin colloid; D019690:Technetium Tc 99m Exametazime