Automated quantitation of peripheral blood neutrophil activation in patients with myocardial ischaemia

Abstract

Background: Coronary ischaemic syndromes are associated with neutrophil activation. The Bayer automated haematology analysers can detect increased light scatter of neutrophil populations, which correlates with neutrophil activation. We aimed to assess the role of an automated analyser in detecting systemic neutrophil activation in peripheral blood samples of patients with coronary ischaemia. Methods: A prospective cross-sectional study was undertaken in 18 patients with chronic stable angina, 9 with unstable angina and 26 normal control subjects. Whole blood samples were taken to assess neutrophil count and light scatter, and serum samples were taken from some patients for assessment of Troponin T, C-reactive protein (CRP) and myeloperoxidase (MPO). In addition, whole blood was stimulated in vitro with interleukin (IL)-8 and N-formyl-methionyl-leucyl-phenylalanine (fMLP) to assess changes in neutrophil light scatter detected by the analyser. Results: Neutrophil light scatter was increased in patients with chronic stable and unstable angina compared to normal control subjects (normal subjects 74.1 (73.3, 75.0) (mean arbitrary units (95% confidence intervals, (CI)) vs. 78.6 (76.9, 80.3) in the chronic stable angina group P<0.001 and 77.1 (75.3, 79.0) in the unstable angina group P<0.007). In vitro stimulation of whole blood produced comparable increases in neutrophil light scatter when morphological changes in neutrophils were demonstrable under electron microscopy. Conclusions: Automated measurement of neutrophil activation by light scatter is possible using the Advia 120 analyser and is superior to a neutrophil count in discriminating groups with angina. This technique may be useful in monitoring disease activity and progression in coronary artery disease and in guiding the use of anti-inflammatory therapies.