Circulating monocyte subpopulations with high expression of angiotensin-converting enzyme predict mortality in patients with end-stage renal disease

Methods. In a prospective observational study, monocyte subpopulations were enumerated and ACE expression was quantified in 74 CKD patients by flow cytometry. Patients were assigned to one of four groups according to monocyte population numbers and ACE expression below and above the respective medians and observed for mortality and cardiovascular events for 46 months. Results. Patients stratified to the 'high CD14(++)CD16(+), high ACE' group (n = 22) had a dramatically enhanced mortality of 70% at 2 years compared to all other patient groups (mortality 14.8%, HR 4.86 [95% CI 2.17-10.86, P < 0.0001]). Atherosclerosis-associated events predominated among the causes of death. Conclusions. This study describes a new combined biomarker of monocyte subpopulation numbers together with high expression of ACE that has a striking predictive value for mortality of CKD patients. Further research into the pathophysiologic background of this observation is warranted.