title: Circulating lymphocyte subsets in normal adults are variable and can be clustered into subgroups.
abstract: BACKGROUND
  Flow cytometry is used to monitor lymphocyte subsets in both the clinical and research settings. An understanding of the degree of inter- and intrasubject variability of these populations is critical for data interpretation.
  
  
  METHODS
  Peripheral blood lymphocytes of 18 healthy adults were analyzed on two separate occasions using a multicolor flow cytometric panel with B, T, and NK cell markers. Variability was calculated using the coefficient of variation and compared between and within individuals using agglomerative clustering.
  
  
  RESULTS
  Each subject appears to have B and T cell subset profiles that are stable over the two time points, but differ from the profiles of other subjects. Thus, the range of measurements for a particular B or T cell subset is larger between subjects and narrower for an individual. In addition, the level of variability correlates inversely with the size of the lymphocyte subset. When lymphocyte profiles are analyzed by agglomerative clustering, replicate samples from the same individual tend to cluster. When single samples from different individuals are analyzed, individuals appear to cluster into different subgroups.
  
  
  CONCLUSIONS
  Variability of lymphocyte subsets is usually greater between individuals than within a single individual and each person appears to have a characteristic profile of lymphocyte subsets. These results underscore the importance of obtaining a baseline value for each subject when investigating the impact of a treatment on lymphocyte subsets over time. These results also highlight the potential utility of cluster analysis as a tool for immune subset profiling and biomarker discovery. © 2011 International Clinical Cytometry Society.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Debora R
authors.initials: DR
authors.lastname: Sekiguchi
authors.forename: Sara B
authors.initials: SB
authors.lastname: Smith
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Sutter
authors.forename: Noah G
authors.initials: NG
authors.lastname: Goodman
authors.forename: Kathleen
authors.initials: K
authors.lastname: Propert
authors.forename: Yoram
authors.initials: Y
authors.lastname: Louzoun
authors.forename: Wade
authors.initials: W
authors.lastname: Rogers
authors.forename: Eline T
authors.initials: ET
authors.lastname: Luning Prak
mesh_terms: D001402:B-Lymphocytes / Q000166:cytology*; D016000:Cluster Analysis; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D016130:Immunophenotyping; D007694:Killer Cells, Natural / Q000166:cytology; D016131:Lymphocyte Subsets / Q000166:cytology; D013601:T-Lymphocytes / Q000166:cytology*