[Evaluation of in vivo labeled cytotoxic T lymphocytes and cytokine-induced killer cells migration and distribution of subcutaneous gastric tumor model in nude mice].

Objective: To investigate the migration and distribution of CTL (cytotoxic T lymphocyte) and CIK (cytokine-induced killer) cells in gastric tumor model.
Methods: Subcutaneous gastric tumor model was established by BGC-823 cancer cells in nude mice. Both CTL and CIK cells were labeled with 99Tc(m) directly and then inoculated into nude mice with subcutaneous tumor by intravenous injection separately. Three mice of each group were evaluated by single-photon emission computerized tomography (SPECT) at 1 h, 6 h and 24 h post-inoculation. After SPECT imaging, 3 mice in each group were sacrificed and got samples of the tumor, liver, spleen, kidney, lung, intestine, etc. The tissue samples were weighed and radioactivity was determined with a well-type scintillation counter. The accumulation of labeled CTL and CIK cells in tissues were expressed as %ID/g (percentage activity of injection dose per gram of tissue) and T/NT (tumor/non-tumor) values were analyzed.
Results: The tracing of both cells in SPECT showed a clear migration path away from the injection point to solid tumor, and can be detected in all organs and tissues such as liver, spleen, kidney, lung and intestine, etc not long after injection. The %ID/g peak values of CTL in organs from the highest to the lowest were as follows: tumor (7.79 +/- 0.46), liver (4.12 +/- 0.51), intestine (2.71 +/- 0.16), kidney (1.44 +/- 0.25), spleen (1.24 +/- 0.12), kidney (1.12 +/- 0.11), and all the T/NTs were above 1. The %ID/g peak values of CIK cells in organs from the highest to the lowest were as follows: liver (6.64 +/- 0.67), tumor (5.47 +/- 0.87), intestine (3.55 +/- 0.23), kidney (2.34 +/- 0.41), spleen (1.45 +/- 0.17), lung (1.27 +/- 0.21), and T/NTs > 1 except for liver. After injection, the %ID/g values of tumor in CTL group were 2.35 +/- 0.28 (1 h), 4.58 +/- 0.52 (6 h) and 7.79 +/- 0.46 (24 h) respectively while the %ID/g values of tumor in CIK group 2.23 +/- 0.46 (1 h), 3.25 +/- 0.70 (6 h) and 5.47 +/- 0.87 (24 h) respectively. At 24 h point, the %ID/g of CTL in tumor was much higher than CIK cells (P < 0.05).
Conclusion: The definite directional tumor-targeting capacity of CTL and CIK cells in tumor-bearing nude mice is promising.