title: Lymphocyte phenotyping to distinguish septic from nonseptic critical illness.
abstract: BACKGROUND
  Clinical signs and symptoms of sepsis are nonspecific and often indistinguishable from those of nonseptic critical illness. This ambiguity frequently delays the diagnosis of sepsis until culture results can confirm the presence or absence of an infectious organism. Lymphocyte phenotyping can be conducted rapidly and may provide information on the presence of infection before culture results are available. In this study, we hypothesized that lymphocyte phenotype can distinguish between septic and nonseptic critical illness.
  
  
  METHODS
  C57Bl/6 mice were subjected to either P aeruginosa pneumonia or lipopolysaccharide-induced acute lung injury (ALI). Animals were sacrificed 24 hours postinjury and splenic lymphocytes were harvested. Additionally, 13 patients in a surgical ICU were enrolled in the study. Whole blood was obtained and lymphocytes were isolated by density gradient centrifugation. Lymphocyte phenotype was identified through flow cytometry after labeling lymphocytes for CD3, CD4, CD8, CD20, CD40, CD69, and CD86 with fluorochrome-conjugated antibodies.
  
  
  RESULTS
  CD69 expression on B cells and CD8+ splenocytes from septic mice was significantly increased compared with acute lung injury mice (p < 0.001 and p < 0.05, respectively). Similarly, CD4+ and CD8+ lymphocytes from septic patients had a two- to threefold increase in the expression of CD69 compared with nonseptic critically ill patients (p < 0.05).
  
  
  CONCLUSIONS
  These data indicated that CD69 expression on lymphocytes may be useful in distinguishing between septic and nonseptic critical illness. Continued investigation into the expression of CD69 during sepsis is warranted.
authors.affiliation: Department of Surgery, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Schwulst
authors.forename: Jared T
authors.initials: JT
authors.lastname: Muenzer
authors.forename: Katherine C
authors.initials: KC
authors.lastname: Chang
authors.forename: Tejal S
authors.initials: TS
authors.lastname: Brahmbhatt
authors.forename: Craig M
authors.initials: CM
authors.lastname: Coopersmith
authors.forename: Richard S
authors.initials: RS
authors.lastname: Hotchkiss
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism*; D051940:B7-2 Antigen / Q000378:metabolism*; D019013:CD40 Antigens / Q000378:metabolism*; D016638:Critical Illness; D004195:Disease Models, Animal; D006801:Humans; D016130:Immunophenotyping; D037181:Lectins, C-Type; D018655:Lymphocyte Count; D016131:Lymphocyte Subsets / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018805:Sepsis / Q000175:diagnosis* / Q000378:metabolism; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D051940:B7-2 Antigen; D019013:CD40 Antigens; D037181:Lectins, C-Type; D000099192:CD69 Antigens