title: Toward new insights on the white blood cell differential by flow cytometry: a proof of concept study on the sepsis model.
abstract: BACKGROUND
  We sought to evaluate, on a model of sepsis, the clinical relevance of new parameters obtained on a white blood cell (WBC) differential by flow cytometry, implemented in the routine workflow of our hematology laboratory.
  
  
  METHODS
  A WBC with differential by flow cytometry was done on 459 patients at admission in intensive care unit. They were retrospectively categorized in having (i) infection or not or (ii) a high gravity score (severe sepsis or septic shock) or not. We analyzed by hierarchical clustering, in a multidimensional manner, 50 parameters provided by the flow cytometric platform in place of the standard seven parameters for a standard differential.
  
  
  RESULTS
  Our approach allows to discriminate on the basis of a WBC differential (i) infected patients at admission based on a 16 parameter signature, with a concordance rate of 72.7% and a specificity of 79.9% and (ii) patients with high gravity score (septic shock or severe sepsis) at admission with a signature of eight parameters, with a concordance rate of 74.7% and a specificity of 75.9%.
  
  
  CONCLUSIONS
  This study shows the clinical relevance of an extended WBC differential to obtain by a flow cytometer integrated into a routine hematology laboratory workflow. Development of such approach implicates the redefinition of the WBC differential by integrating new parameters.
authors.affiliation: CHU Rennes, Laboratoire d'Hématologie, Pôle de Biologie, F-35033 Rennes, France. mikael.roussel@chu-rennes.fr
authors.forename: Mikael
authors.initials: M
authors.lastname: Roussel
authors.forename: Antoine
authors.initials: A
authors.lastname: Gros
authors.forename: Arnaud
authors.initials: A
authors.lastname: Gacouin
authors.forename: Nolwenn
authors.initials: N
authors.lastname: Le Meur
authors.forename: Yves
authors.initials: Y
authors.lastname: Le Tulzo
authors.forename: Thierry
authors.initials: T
authors.lastname: Fest
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007362:Intensive Care Units; D007958:Leukocyte Count / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018805:Sepsis / Q000175:diagnosis*; D012720:Severity of Illness Index