Atherosclerosis Risk in Communities (ARIC) Carotid MRI flow cytometry study of monocyte and platelet markers: intraindividual variability and reliability.
BACKGROUND
Cellular markers help identify different components of a pathological process and may contribute to the diagnosis, prognostic assessment, and management of patients with suspected syndromes. Flow cytometry can be used to accurately assess markers of platelet and leukocyte activation and cellular aggregation in whole blood. To use cell markers as predictors of disease requires that they be measured reliably and show modest within-individual, day-to-day variation.


METHODS
We used whole blood flow cytometry to analyze monocyte and platelet markers in the Atherosclerosis Risk in Communities (ARIC) Carotid MRI study. We estimated laboratory variability using 20 split samples, process variation using replicate blood tubes taken from 112 subjects, and biologic plus process variation using replicate blood samples taken 4-8 weeks apart from 55 people.


RESULTS
For most analytes, the laboratory CV was <10% (mean 3.6%, range 0%-14.5%) and reliability was excellent (75% of analytes had R > 0.90). Reliability coefficients based on repeat-visit data indicated substantial to high repeatability (R > 0.60) for CD14, Toll-like receptor (TLR)-2, CD162, CD61, CD41, CD62P, CD154, and platelet-leukocyte aggregates. In contrast, TLR-4, CD45, myeloperoxidase (MPO), and cyclooxygenase (COX)-2 had slight to moderate repeat visit reliability.


CONCLUSIONS
The high repeatability results for selected platelet and monocyte markers indicate that they can be reliably measured in multicenter studies with delayed sample processing, provided that rigorous standardization of sample collection, shipping, and flow cytometry procedures is applied.
Catellier
Diane J
DJ
Collaborative Studies Coordinating Center, University of North Carolina at Chapel Hill, Department of Biostatistics, Chapel Hill, NC 27514-4145, USA. diane_catellier@unc.edu
Aleksic
Nena
N
Folsom
Aaron R
AR
Boerwinkle
Eric
E
D001741:Black or African American; D000368:Aged; D015703:Antigens, CD / Q000032:analysis; D015415:Biomarkers / Q000032:analysis; D001792:Blood Platelets / Q000166:cytology* / Q000378:metabolism; D002340:Carotid Artery Diseases / Q000097:blood / Q000175:diagnosis*; D015331:Cohort Studies; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D008297:Male; D009000:Monocytes / Q000166:cytology* / Q000378:metabolism; D011446:Prospective Studies; D015203:Reproducibility of Results; D044465:White People
D015703:Antigens, CD; D015415:Biomarkers