P382 Monocytic membrane-bound Angiotensin converting enzyme (ACE) surface expression is elevated hemodialysis patients with CHD and/or pVD.
Chr.Ulrich, G.Heine, P.Garcia, H.Köhler, M.Girndt
Innere Medizin IV, Universitätskliniken des Saarlandes, Homburg.

Numerous classical primary risk factors such as hypertension, diabetes mellitus and hypercholesterolemia result in an increased prevalence of atherosclerotic cardiovascular disease in hemodialysis patients (HD). However, these classic risk factors do not sufficiently explain the highly increased risk of cardiovascular events in HD patients. In addition, an activated renin-angiotensin system (RAS) may be a key player in the complex cascade of events leading to a reduction in the arterial lumen and obstruction of blood vessels.

Because RAS exists not only as an endocrine tissue system resulting in local production of Angiotensin II (Ang II) but also as a paracrine system leading to increased levels of circulating Ang II, we compared the monocytic ACE levels of HD patients showing signs of coronary heart disease (CHD) and/or peripheral vascular disease (pVD) with those of patients without any history of cardiovascular events.

Surface expression (mean fluorescence intensity, MFI) and percentage of monocytes staining positive for ACE were analysed by 4-colour flow cytometry using two different clones of anti-CD143 (ACE: clone 9B9 and i2h5).

Both the frequency of monocytes staining positive for ACE (CHD/pVD+: 38.1±15.6% vs. CHD/pVD -: 26.4±14.2%, p<0.01) and the cell surface expression of monocytic ACE (MFI: CHD/pVD +: 4.7±1.9 vs. CHD/pVD -: 3.5±1.9, p<0.01 were significantly increased in patients with CHD/pVD as compared to patients showing no signs of cardiovascular disease.

These results indicate that the determination of the monocytic ACE frequency and surface expression may be a valuable tool for the identification of high risk individuals among HD patients. Circulating monocytes expressing high levels of ACE could directly be implicated in atherosclerotic processes. Further prospective studies will address, whether the analysis of ACE expression may serve as a prognostic marker of early CHD/pVD in HD patients.