The primary goal of the project is to determine if cyclic AMP and cyclic GMP are closely associated with changes in the activity of alveolar macrophages. Peritoneal and alveolar macrophages from normal and immune animals will be compared. Several agents demonstrated to promote the killing of tumor cells by macrophages will be tested including bacterial endotoxin, BCG cell wall material and some crude lymphokine preparations containing macrophage activation factor. Several specific biochemical and functional parameters of macrophages will be measured: such as lysosomal enzyme content, glucose oxidation through the hexose monophosphate shunt, glucosamine incorporation, phagocytosis, chemilumiescence, and intracellular levels of cyclic AMP, cyclic GMP and cyclic AMP dependent protein kinase. Time course studies of changes in the above parameters will be done using alveolar macrophages from normal and BCG-immunized rabbits, peritoneal macrophages from normal and BCG immunized mice, and a continuous macrophage-like cell line, J774.l. Some additional studies are also planned to assess the effects of insulin on monocytes and macrophages.