Technetium-99m leucocyte labelling using a lyophilised stannous fluoride colloid kit

Major problems are associated with this standard method of radiolabelling of leucocytes with 99mTc stannous fluoride colloid. Low solubility of stannous fluoride prolongs reagent preparation time and reagents are unstable in solution, even when stored frozen. There is substantial loss of activity during the procedure, half of the techneitum-99m activity in the colloid labelling vial being lost by binding to the container. These problems were addressed by the development of a sterile pyrogen-free lyophilised kit. Technetium-99m leucocytes labelled using this kit were tested for viability and evaluated by electron microscopy to demonstrate phagocytic labelling. Studies were performed in normal volunteers to determine reproducibility of labelling and in vivo studies were performed in patients with focal sepsis to define clinical efficacy of the method. It is concluded that the lyophilised kit developed is sterile, stable and convenient to use. 2 refs., 1 tab., ills