This project will investigate: 1) using radioactive metabolic precursors, whether, 99m-Technetium (99m-Tc) and 111-Indium (111-In)-labeled leukocytes are biochemically inhibited when studying the following cell functions: (a) DNA, RNA and protein synthesis; (b) Reproductive ability; (c) Response to mitogens, PHA, ConA, LPS; (d) Ability of the radionuclide-labeled immune leukocytes to act as cytotoxic cells against 51-Chromium-labeled tumor cells. 2) Using 99m-Tc or 111-In-labeled Murine (Moloney) Sarcoma Virus (MSV) tumor cells immunized C57B1/6 mouse spleen leukocytes, we will study the in vivo MSV tumor site accumulation of these cells using gamma camera imaging and quantitation by sacrifice of the animals and measurement of individual organ tissue and tumor reactivity.