Angiotensin II receptor on BALF macrophages from Japanese patients with active sarcoidosis

Background: Serum angiotensin converting enzyme (ACE) activity and its chan ges are important markers for disease activity in patients with sarcoidosis . We earlier reported that ACE and its enzymatic product, angiotensin II (A -II), might play a role in maintaining macrophage/T lymphocyte alveolitis b y enhancing an accessory function of macrophages in chronic active cases wi th sarcoidosis. Aim of the work and methods: We examined whether A-II recep tor is present on BALF macrophages by a receptor binding assay using I-125- labeled A-II, and by amplification of A-II receptor gene transcripts using RT-PCR methods and quantification of the amounts of transcripts by HPLC. Re sults: The receptor binding assay suggested that specific binding of A-II t o BALF macrophages was somewhat more prevalent in active sarcoidosis than i n controls. A specific band for A-II receptor was detected by RT-PCR. A-II receptor gene expression was standardized as the ratio to beta-actin. An in creased ratio was shown in active sarcoidosis (0.70 +/- 0.19; n = 14) compa red to inactive cases (0.14 +/- 0.06; n = 5; p = 0.023) and healthy subject s (0.15 +/- 0.09; n = 5, p = 0.029). The ratio correlated positively with t he percentage of BALF T lymphocytes (r = 0.60, p = 0.0056), and negatively with BALF macrophages (r = 0.60, p = 0.0055). No difference was detected be tween nonsmokers and smokers. Conclusion: The amounts of A-II receptor gene expression of BALE macrophages correlated with disease activity in patient s with pulmonary sarcoidosis.