Arginase production by peritoneal macrophages: A new assay

The arginase activity of murine mononuclear cells was assessed with a new highly sensitive radioassay. Adherent mononuclear cells obtained by peritoneal lavage from normal mice contain significant quantities of enzyme. This was released in culture and continued synthesis could be blocked with cycloheximide. Arginase activity was not found in adherent or non-adherent mononuclear cells from the spleen. Peritoneal cells obtained from mice infected with P. berghei or from mice injected with LPS intraperitoneally had higher arginase activity than cells from control mice.