Differential effects of captopril and enalapril, two angiotensin converting enzyme inhibitors, on immune reactivity in experimental lupus disease.

We have previously demonstrated that Captopril, an inhibitor of angiotensin converting enzyme (ACE), ameliorates experimental systemic lupus erythematosus in inbred MRL lpr/lpr (MRL/l) mice. In contrast, Enalapril, another ACE inhibitor with antihypertensive properties but lacking a thiol group, did not show similar beneficial effects. To better understand the mode of action of captopril in the autoimmune disease we have evaluated its immunomodulatory properties with special emphasis on antigen-specific and polyclonal B- and T-cell activation. The results obtained strongly suggest that Captopril exerts its immunomodulatory effects through stimulation of T-lymphocytes.