A Commercial Preparation of Catalase Inhibits Nitric Oxide Production by Activated Murine Macrophages: Role of Arginase

Catalase is widely used as a pharmacological probe to evaluate the role of hydrogen peroxide in antimicrobial activities of phagocytic cells. This report demonstrates that the ability of a commercial preparation of catalase to inhibit concomitantly macrophage antimycobacterial activity and production of reactive nitrogen intermediates can be attributed, at least in part, to the depletion of l-arginine by contaminating arginase. In experimental systems that employ pharmacological probes, the existence of nonspecific effects should be considered in data interpretation.