Gallium 67 in the Human Lymphoid Cell Line U-715: Uptake, Cytotoxicity and Intracellular Localization

The selective uptake of the Auger- and internal conversion electrons emitting radionuclide 67Ga in maligant tumours may have therapeutic potential. We studied several factors which might affect the uptake and radiotoxicity of 67Ga in the human lymphoma cell line U-715. The 67Ga uptake was dependent on transferrin in a dose-dependent manner. The highest 67Ga uptake was found in the presence of 50 µg/ml purified human transferrin. Serum components other than transferrin negatively influenced the 67Ga uptake. Cells were adapted to a serum-free medium in which cells could be maintained for months and without factors disturbing 67Ga uptake. We demonstrated that there was a positive correlation between cell viability and 67Ga uptake (r = 0·97). Preculturing of cells in iron- and transferrin-deficient medium prior to 67Ga uptake led to upregulation of the transferrin receptor and a three-fold increase of 67Ga uptake. Uptake in these cells could be blocked by 72% by anti-transferrin-receptor monoclonal antibodies...