title: In vivo platelet activation in critically ill patients with primary 2009 influenza A(H1N1).
abstract: BACKGROUND
  Changes in platelet reactivity during 2009 influenza A(H1N1) (A[H1N1]) have not been characterized.
  
  
  METHODS
  We prospectively examined platelet activation and cytokine responses in patients with A(H1N1) (n = 20), matched patients with bacterial pneumonia (n = 15), and nonhospitalized, healthy control subjects (n = 10).
  
  
  RESULTS
  Platelet-monocyte aggregation was higher in patients with A(H1N1) (21.4% ± 4.7%) compared with patients with pneumonia (10.9% ± 3.7%) and control subjects (8.1% ± 4.5%, P < .05). Similarly, PAC-1 (antibody that binds to the active conformation of integrin α(IIb)β(3)) binding to platelets is increased in patients with A(H1N1) (9.5% ± 4.7%) compared with patients with pneumonia (1.0% ± 0.7%) and healthy subjects (0.61% ± 0.15%, P < .10). PAC-1 binding was twofold higher in patients with A(H1N1) with shock vs those without shock. IL-6 levels were elevated in patients with A(H1N1), indicating systemic inflammation consistent with activation of circulating platelets.
  
  
  CONCLUSIONS
  These findings, derived from a small but documented cohort of patients, demonstrate that platelet activation responses during A(H1N1) are enhanced-exceeding responses in patients with bacterial pneumonia-and provide new evidence that platelets may contribute to inflammatory responses during A(H1N1).
authors.affiliation: Division of General Internal Medicine, University of Utah School of Medicine, Salt Lake City; Department of Internal Medicine, and the Program in Molecular Medicine, University of Utah School of Medicine, Salt Lake City. Electronic address: matthew.rondina@hsc.utah.edu.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Rondina
authors.affiliation: Department of Internal Medicine, and the Program in Molecular Medicine, University of Utah School of Medicine, Salt Lake City.
authors.forename: BreAnna
authors.initials: B
authors.lastname: Brewster
authors.affiliation: The Division of Pulmonary and Critical Care Medicine, University of Utah School of Medicine, Salt Lake City; The Intermountain Medical Center, Division of Critical Care, Murray, UT.
authors.forename: Colin K
authors.initials: CK
authors.lastname: Grissom
authors.affiliation: The Division of Pulmonary and Critical Care Medicine, University of Utah School of Medicine, Salt Lake City.
authors.forename: Guy A
authors.initials: GA
authors.lastname: Zimmerman
authors.affiliation: Department of Internal Medicine, and the Program in Molecular Medicine, University of Utah School of Medicine, Salt Lake City.
authors.forename: Diana H
authors.initials: DH
authors.lastname: Kastendieck
authors.affiliation: The Division of Pulmonary and Critical Care Medicine, University of Utah School of Medicine, Salt Lake City.
authors.forename: Estelle S
authors.initials: ES
authors.lastname: Harris
authors.affiliation: The Division of Pulmonary and Critical Care Medicine, University of Utah School of Medicine, Salt Lake City; Department of Internal Medicine, and the Program in Molecular Medicine, University of Utah School of Medicine, Salt Lake City.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Weyrich
mesh_terms: D018806:APACHE; D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D015897:Comorbidity; D016638:Critical Illness; D054641:Dual Specificity Phosphatase 2 / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000097:blood* / Q000401:mortality / Q000821:virology; D015850:Interleukin-6 / Q000097:blood; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D015539:Platelet Activation; D011446:Prospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; C517032:DUSP2 protein, human; D054641:Dual Specificity Phosphatase 2