IL2 and neoplasm: According to in vivo bio-distribution studies, using T-cell imaging tracers, such as 99mTc-sum IL-2 (27) or 111In-oxine-labeled lymphocyte (28), the dynamic infiltration of adoptive T cells can be investigated, and these studies showed significantly increased uptake of T-cell tracers in some immune organs, including liver, spleen, and tumor-draining lymph node.