title: Biological variability of lymphocyte subsets of human adults' blood.
abstract: BACKGROUND
  Alterations in lymphocyte subpopulations are present in several immune diseases, and clinicians and researchers recognise the importance of investigating the distribution and changes in lymphocyte subsets over relatively long periods of time in order to evaluate the effectiveness of treatment and follow the course of disease. Yet further insight is required on the biological variability (BV) of lymphocyte subsets, which is crucial to the correct interpretation of longitudinal changes and provides essential information for setting desirable quality specifications and defining the usefulness of reference values.
  
  
  METHODS
  Four-colour-flow cytometry was used to investigate the BV of lymphocyte populations (LP) in the peripheral blood of 20 healthy adults recruited from our laboratory staff and followed for three months. The total lymphocyte count was measured, and the relative frequencies determined for T-cells (CD3+), T-helper cells (CD3+CD4+), cytolytic T-cells (CD3+CD8+), B-cells (CD3-CD19+), NK-cells (CD3-CD16+/56+), non-MHC restricted cytolytic T-cells (CD3+CD56+) and activated T-cells (CD3+HLA-DR+).
  
  
  CONCLUSIONS
  Data on the components of BV were applied to set quality specifications for allowable precision, bias and total error. Analytical performances were established, and they were more than desirable for all the markers considered in our study. By comparing within-subject and between-subjects BV, we were able to define the uselessness of reference ranges in the evaluation of changes in CD serial results. Data on within-subject BV and analytical precision were thus used to determine the reference change values, in order to identify the significance of changes in serial results. The findings made in the present study provide further evidence of the relevance of BV in the evaluation of immunological markers of LP.
authors.affiliation: Department of Laboratory Medicine, University Hospital of Padova, Via Giustiniani 2, 35128 Padova (PD), Italy. Electronic address: francesca_tosato@yahoo.it.
authors.forename: Francesca
authors.initials: F
authors.lastname: Tosato
authors.forename: Daniela
authors.initials: D
authors.lastname: Bernardi
authors.forename: Maria Colomba
authors.initials: MC
authors.lastname: Sanzari
authors.forename: Giorgia
authors.initials: G
authors.lastname: Pantano
authors.forename: Mario
authors.initials: M
authors.lastname: Plebani
mesh_terms: D000328:Adult; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology; D001402:B-Lymphocytes / Q000145:classification / Q000166:cytology* / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D015870:Gene Expression; D014644:Genetic Variation / Q000276:immunology; D064368:Healthy Volunteers; D006801:Humans; D016130:Immunophenotyping; D007694:Killer Cells, Natural / Q000145:classification / Q000166:cytology* / Q000276:immunology; D018655:Lymphocyte Count; D016131:Lymphocyte Subsets / Q000145:classification / Q000166:cytology* / Q000276:immunology; D008875:Middle Aged; D012016:Reference Values; D013601:T-Lymphocytes / Q000145:classification / Q000166:cytology* / Q000276:immunology
chemical_list: D015703:Antigens, CD
keywords: Biological variability; Lymphocyte subsets; Quality specifications