Imaging Lung Clearance of Radio labeled Tumor Cells to Study Mice with Normal, Activated or Depleted Natural Killer (NK) Cells

摘要

Lung clearance of~(51)CR and ~(125)Ⅰ iododeoxyuridine (IUDR) labeled cancer cells assess NK cell activity. It is desirable to develop noninvasive imaging technique to assess NK activity in mice. We labeled target YAC-1 tumor cells with ~(125)Ⅰ ~(111)In. ~(99m)Tc, or ~(67)Ga and injected Ⅰ.Ⅴ. into three groups of BALB/c mice. Animals were treated with medium (group Ⅰ), 300mg/kg cyclophosmamide (CY) to kill NK cell (group Ⅱ), or anti-LY49C/l) (ab')_2 mAb to augment NK function (group Ⅲ). Lungs were removed 15 min or 2 h later for tissue counting. Control and treated mice were imaged every 5 min with a scintillating camera for 1 h after 15 min of infusion of the ~(111)In labeled cells. Lung clearance increased after 15 min (lodging: 60-80%) and (2 h retention: 3-7%). Similar results were obtained with all the isotopes studied. Images distinguished the control and treated mice for lung activity. Cells labeled with ~(111)In, ~(99m)Tc or ~(67)Ga are cleared similar to those labeled with ~(51)Cr or ~(125)Ⅰ. NK cell destruction of tumor cells may be assessed by noninvasive imaging method either by SPECT (~(99m)Tc, ~(111)In, ~(67)Ga) or by PET (~(68)Ga).