ACE is a carboxy-terminal peptidyl dipeptidase which can be produced by granuloma macrophages and possibly by other components of the granuloma. ACE activity is influenced by regulatory T cells. This enzyme may be important in mediating and/or modulating inflammation. One mechanism involves the generation of angiotensin II which can effect inflammatory reactions. Although unstudied, ACE may also be an important inactivator of bradykinin and various neuropeptides which in turn may participate in the immunoregulation of the granuloma. Thus, therapeutic strategies designed to alter ACE activity within granulomas may alter the size, composition and ultimate resolution of these lesions.