title: A new 99mTc labelling method for leucocytes: in vitro and in vivo comparison with 99mTc-HMPAO.
abstract: A new method for the labelling of mixed leucocytes with 99mTc-tropolone was optimized and compared with a 99mTc-HMPAO leucocyte labelling procedure in vitro and in vivo. In the present study, leucocytes obtained from patients suffering from Crohn's disease, were isolated and labelled with 99mTc-HMPAO or labelled according the new 99mTc-tropolone procedure using 9.8 mM tropolone, 1 microM stannous chloride and 0.8 mM potassium borohydride (KBH4) at pH 5.5-6. Labelling efficiency with 99mTc-tropolone yielded 92 +/- 3%, which is higher compared to the 99mTc-HMPAO labelling procedure (64 +/- 13%) using 10(8) of leucocytes. In vitro stability and viability of both the tropolone and the HMPAO labelled cells was investigated. The viability test of the 99mTc-labelled leucocytes was performed in autologous plasma at 37 degrees C and compared with unlabelled leucocytes. After 18 hours of incubation a significant (P < 0.05) higher stability was observed for 99mTc-tropolone labelled leucocytes (84 +/- 5%) compared with that of 99mTc-HMPAO labelled leucocytes (73 +/- 5%). The viability of the 99mTc-labelled leucocytes observed for both labelling procedures was similar to unlabelled leucocytes. In vivo experiments were performed in mice. 99mTc-tropolone or 99mTc-HMPAO labelled murine mixed leucocytes were injected in mice, with a Staphylococcus aureus ATCC 25923 thigh infection. Analysis of scintigraphic images yielded a faster clearance of the 99mTc-tropolone labelled leucocytes. This was most likely due to a significant (P < 0.02) higher liver uptake at 4 hours after administration of the 99mTc-tropolone labelled leucocytes (19%) in comparison with 99mTc-HMPAO labelled cells (9%). Faster and significant (P < 0.02) higher accumulation of the 99mTc-tropolone labelled leucocytes was observed at the site of infection compared with 99mTc-HMPAO labelled leucocytes at all time-intervals after the administration of the 99mTc-labelled leucocytes. The new 99mTc-tropolone leucocyte labelling procedure, offers an attractive low-cost agent for research purposes.
authors.affiliation: Department of Diagnostic Radiology and Nuclear Medicine, University Hospital, Leiden, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Welling
authors.forename: H I
authors.initials: HI
authors.lastname: Feitsma
authors.forename: D
authors.initials: D
authors.lastname: Blok
authors.forename: W
authors.initials: W
authors.lastname: Calame
authors.forename: G J
authors.initials: GJ
authors.lastname: Ensing
authors.forename: W
authors.initials: W
authors.lastname: Goedemans
authors.forename: E K
authors.initials: EK
authors.lastname: Pauwels
mesh_terms: D000038:Abscess / Q000000981:diagnostic imaging; D000818:Animals; D001894:Borohydrides; D002470:Cell Survival; D002845:Chromatography; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007553:Isotope Labeling; D007962:Leukocytes; D008297:Male; D051379:Mice; D015609:Organotechnetium Compounds; D010091:Oximes; D011877:Radionuclide Imaging; D013203:Staphylococcal Infections / Q000000981:diagnostic imaging; D019690:Technetium Tc 99m Exametazime; D017971:Tin Compounds; D014334:Tropolone
chemical_list: D001894:Borohydrides; D015609:Organotechnetium Compounds; D010091:Oximes; D017971:Tin Compounds; C028371:potassium borohydride; C023599:stannous chloride; D019690:Technetium Tc 99m Exametazime; D014334:Tropolone