Functional upregulation of granulocytes labeled with technetium-99m-HMPAO and indium-111-oxinate.
Indium-111-oxinate-labeled granulocytes have been used in vivo for several years for the detection of abscesses. Technetium-99-m-hexamethylpropyleneamine oxime (99mTc-HMPAO) labeling has more recently been described.


METHODS
The influence of radiolabeling by both radiotracers on adhesion glycoprotein CD11b quantification was studied in quiescent and formyl-methionylleucylphenylalanine (fMLP)-activated neutrophils (PMN). Adhesion was assessed on human umbilical endothelial cells (HUVEC) as well as the repercussion of the granulocyte labeling on HUVEC viability (neutral red) and metabolic activity (MTT). Chemotaxis of PMN was evaluated by measuring migration under agarose with fMLP as chemoattractant. We also measured phagocytosis and the production of hydrogen peroxide induced by staphylococcus aureus.


RESULTS
Whereas whole functional integrity is maintained after labeling, most of the functions (CD11b expression, adhesion, HUVEC metabolic activity) are up-regulated while chemotaxis is decreased in the presence of both radiotracers. Indium-111-oxinate induces larger alterations than 99mTc-HMPAO.


CONCLUSIONS
These data were obtained in normal volunteers. In patients, alterations due to the in vitro labeling procedure, in addition to potential functional alterations caused by the underlying pathology, should be taken into account during image interpretation.
Bertrand-Caix
J
J
INSERM-U. 306, University of Bordeaux II, France.
Freyburger
G
G
Bordenave
L
L
Labrouche
S
S
Bareille
R
R
Baquey
C
C
Ducassou
D
D
Lefebvre
F
F
D002478:Cells, Cultured; D002634:Chemotaxis, Leukocyte; D004730:Endothelium, Vascular / Q000166:cytology; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007205:Indium Radioisotopes; D007553:Isotope Labeling; D008213:Lymphocyte Activation; D016177:Macrophage-1 Antigen / Q000378:metabolism; D008297:Male; D009504:Neutrophils / Q000502:physiology; D009942:Organometallic Compounds; D015609:Organotechnetium Compounds; D010091:Oximes; D015125:Oxyquinoline / Q000031:analogs & derivatives*; D010587:Phagocytosis; D016897:Respiratory Burst; D019690:Technetium Tc 99m Exametazime; D015854:Up-Regulation
D007205:Indium Radioisotopes; D016177:Macrophage-1 Antigen; D009942:Organometallic Compounds; D015609:Organotechnetium Compounds; D010091:Oximes; C032950:indium oxine; D019690:Technetium Tc 99m Exametazime; D015125:Oxyquinoline; D006861:Hydrogen Peroxide