Imaging of lymphoid structures with indium-111-labeled lymphocytes

The ability of indium-111 (111In)-oxine-labeled syngeneic lymphocytes to migrate normally and their suitability for imaging both normal lymphoid structures and those with metastatic disease were assessed. Sixty-two ACI rats were studied, 34 of which received injections in the left foot pad with 1 X 10(6) syngeneic H-4-II-E hepatoma cells nine to 44 days before imaging. Most animals were bearing palpable tumors when imaged. In 53 experiments, 1-6 X 10(8) 111In-oxine-labeled lymphocytes with a labeling concentration of 5-80 microCi/10(8) cells were injected intravenously. Gamma camera images were obtained 22 hours later. After the last image, the animals were killed. The lymph nodes, liver, spleen, lungs, and left femur were dissected, and the recovered radioactivity was determined in a gamma well counter. Lymph nodes could be partially or completely visualized in 70% of the animals (15 tumor-bearing and 16 normal out of 44 technically satisfactory experiments). Large metastatic nodes were seen clearly. Lymphocytes labeled with 111In-oxine exhibited a normal migration from blood to lymph nodes.