Chemotaxis, viability, and labeling stability of leukocytes labeled with (99m)Tc-exametazime stabilized with methylene blue.
The in vitro viability, chemotaxis, and labeling stability of leukocytes labeled using (99m)Tc-exametazime stabilized with methylene blue were evaluated and compared with those obtained using nonstabilized (99m)Tc-exametazime.


METHODS
Two identical leukocyte populations, from 30 healthy donors, were labeled simultaneously using freshly prepared and 2-h-old stabilized (99m)Tc-exametazime. The following quality control techniques were performed on each labeled leukocyte sample: eosin Y staining, chemotaxis radioassay, and labeling stability at 2 h after labeling.


RESULTS
Eosin Y staining showed a cell viability of at least 98% in all samples, without a significant statistical difference between the populations. Chemotactic indices obtained with leukocytes labeled with freshly prepared, unstabilized (99m)Tc-exametazime were statistically greater than those obtained using (99m)Tc-exametazime stabilized with methylene blue (z = 2.41; P<0.02). Labeling stability at 2 h after labeling was the same for both populations.


CONCLUSIONS
The use of (99m)Tc-exametazime stabilized with methylene blue for leukocyte radiolabeling does not affect either cell membrane integrity or labeling stability but can cause a decrease in the cell chemotactic capacity that discourages its clinical use.
Roca
M
M
Radiopharmacy Unit, Nuclear Medicine Department, L'Hospitalet de Llobregat, Ciutat Sanitària Universitària de Bellvitge, Barcelona, Spain.
Iglesias
F
F
García
V
V
Armero
F
F
Díaz
M C
MC
D002470:Cell Survival; D002634:Chemotaxis, Leukocyte; D004355:Drug Stability; D004801:Eosine Yellowish-(YS); D006801:Humans; D007553:Isotope Labeling; D007962:Leukocytes / Q000502:physiology; D008751:Methylene Blue; D019275:Radiopharmaceuticals; D013194:Staining and Labeling; D019690:Technetium Tc 99m Exametazime
D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime; D008751:Methylene Blue; D004801:Eosine Yellowish-(YS)