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(Circulation. 2007;115:e186.)
© 2007 American Heart Association, Inc.

Correspondence

Letter by Krishnan et al Regarding Article, "Platelet Expression Profiling and Clinical Validation of Myeloid-Related Protein-14 as a Novel Determinant of Cardiovascular Events"

Unni Krishnan, MRCP; Alison H. Goodall, PhD

Department of Cardiovascular Sciences, University of Leicester, Clinical Sciences Wing, Glenfield Hospital, Leicester, United Kingdom

Peter Bugert, PhD

Molecular Biology Laboratory, Institute of Transfusion Medicine and Immunology, University of Heidelberg, Medical Faculty of Mannheim Mannheim, Germany

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

The article by Healy et al¹ raises interesting possibilities in coronary artery disease by suggesting a new candidate biomarker for stable coronary artery disease and postulating a novel source for myeloid-related protein-14 (MRP-14). In our opinion, however, there are some factors that may need to be considered before platelets can be determined to be a source of MRP-14.

Patients with ST-elevation myocardial infarction in the study¹ had significantly raised leukocyte counts, a factor that was not included in the multivariate model. Because leukocytes are a well-known source of MRP-14, this could explain the raised plasma levels of this protein in the patient group. Epidemiological studies suggest that leukocyte count is an independent predictor of coronary events in asymptomatic individuals. It would, therefore, be expected that leukocyte counts would be raised in the patient cohort in the validation study, significantly affecting the level of MRP-14 in plasma.

Although leukocyte contamination of the platelet preparations was monitored by analysis of CD45+ events by flow cytometry, this method may not provide the sensitivity to accurately detect contamination by leukocytes. In addition, this method may fail to detect leukocyte microparticles that may lack the CD45 antigen but that would be isolated with the platelets and could contribute to the mRNA pool. Given the 12 500-fold relative abundance of mRNA in leukocytes compared with platelets² only, tiny levels of leukocyte contamination could account for the presence of MRP-14 in the platelet transcriptome.

The authors suggest that previous work in platelet transcriptome profiling . . . [Full Text of this Article]

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Circulation 2007 115: 677. [Extract] [Full Text]