Angiotensin-1-converting enzyme activity of murine macrophages isolated from granulomas elicited by eggs of Schistosoma mansoni.

Angiotensin-1-converting enzyme (A1CE) activity was assessed in macrophages isolated from hepatic egg granulomas at 7 and 20 weeks after the infection of mice with Schistosoma mansoni. At 2 h after isolation, granuloma macrophages (GM) from chronically infected mice (20 weeks) displayed significantly higher levels of A1CE than did GM from mice 7 weeks after infection; both of the values were significantly higher than control peritoneal resident macrophages from normal mice. A1CE activity in GM and their respective culture supernatants declined over a 72-h period of in vitro cultivation; however, the decline was abrogated with the addition of dexamethasone to the culture medium. GM from athymic mice displayed significantly higher A1CE activity than did those from normal controls. Our data confirm and extend previous findings of others that GM are a major source of A1CE in murine schistosomiasis and that lymphocyte function may regulate GM A1CE production.