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 rep ort demonstrates that the ability of a commercial preparation of catalase t o inhibit concomitantly macrophage antimycobacterial activity and productio n of reactive nitrogen intermediates can be attributed, at least in part, t o the depletion of L-arginine by contaminating arginase. In experimental sy stems that employ pharmacological probes, the existence of nonspecific effe cts should be considered in data interpretation.