A new method for rapid technetium-99m labelling of leucocytes: functional cell studies in vitro

Abstract

Sundrehagen E, Benestad HB, Heikkilä R, Hersleth IB, Siebke M, Strøm-Gundersen I. A new method for rapid technetium-99m labelling of leucocytes: functional cell studies in vitro. Scand J Clin Lab Invest 1985; 45: 717–724.

The aim of this study was to assess the cytotoxicity of a new leucocyte-labelling method, which may be used clinically to localize inflammatory and immune reactions. Human blood leucocytes, their mononuclear sub-population, and mouse mononuclear bone marrow cells were labelled with ^99mTc for 30–45 min, washed once, and then evaluated in various functional assays. The new procedure includes [^99mTc]-labelling with a bisalt method, in the presence of dihydroxybenzoic acid as an intermediate antioxidant-complexing stabilizer, and a carboxylic acid salt of stannous ions as a reducing agent. To challenge the method, cells were labelled about two orders of magnitude more heavily in these initial methodological studies than in on-going clinical trials. Labelled leucocytes ingested latex beads as readily as the controls, but migrated chemotactical-ly and randomly somewhat slower than the control cells. The lymphocytes were triggered by PHA and Con A in a normal way. However, lymphocytes and haemopoietic progenitor cells exposed to radiation for several days, were killed by the isotope doses used, of which about 2% (i.e. 20 MBq) were bound per million cells. All deleterious effects were apparently due to irradiation, and the labelling procedure itself did not damage the cells.

Key Words:

• chemotaxis
• dihydroxybenzoic acid
• haemopoiesis
• lymphocyte transformation
• phagocytosis
• stannous ions
• [^99mTc]-labelling