title: Cell mediated immune responses following revaccination with an influenza A/H5N1 vaccine.
abstract: OBJECTIVE
  The study aims were to determine whether inactivated influenza A/H5N1 vaccine administration elicited cell mediated immune (CMI) responses and the impact of adjuvant, vaccine dose and subject age on these responses.
  
  
  METHODS
  Adults who were previously primed with either adjuvanted or unadjuvanted, inactivated, A/H5N1/Vietnam/1203/2004 (Clade 1) vaccine or unprimed (received placebo) in previous vaccine studies were randomized to receive one (primed) or two (unprimed) 15- or 90-mcg doses of inactivated, A/H5N1/Indonesia/05/05 (Clade 2) vaccine. Peripheral blood mononuclear cells (PBMCs) were collected and analyzed from a subset of vaccinees to assess CMI responses using IFN-γ and granzyme B ELISPOT assays. Cytokine measurements were performed on PBMC supernatants after stimulation with H5N1 virus.
  
  
  RESULTS
  PBMCs were available from 177 participants; 88 and 89 received 15-mcg and 90-mcg of unadjuvanted clade 2 vaccine, respectively. Following H5N1 clade 1 stimulation, IFN-γ but not granzyme B normalized spot-forming cell numbers had statistically significant increased numbers at each of the post-vaccination timepoints compared to baseline in pooled analyses of all vaccine doses and age groups. Clade 2 stimulation resulted in statistically significant increased numbers of IFN-γ cells only 180 days following the last vaccination. Responses were similar among younger and older study participants, as were responses among those primed with alum-adjuvanted or non-adjuvanted clade 1 H5N1 vaccines. The dosage of clade 2 vaccine did not impact CMI responses among primed subjects, but responses were statistically significantly greater in unprimed recipients of the 90-mcg dosage compared to unprimed recipients of the 15-mcg dosage. IFN-γ levels in the supernatants of stimulated PBMC were strongly correlated with IFN-γ ELISPOT results.
  
  
  CONCLUSIONS
  CMI responses occur in adults administered influenza A/H5N1 inactivated influenza vaccine.
authors.affiliation: Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, United States.
authors.forename: Innocent N
authors.initials: IN
authors.lastname: Mbawuike
authors.affiliation: Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, United States; Department of Medicine, Baylor College of Medicine, Houston, TX, United States. Electronic address: ratmar@bcm.edu.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Atmar
authors.affiliation: Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, United States; Department of Medicine, Baylor College of Medicine, Houston, TX, United States.
authors.forename: Shital M
authors.initials: SM
authors.lastname: Patel
authors.affiliation: Department of Medicine, Baylor College of Medicine, Houston, TX, United States.
authors.forename: David B
authors.initials: DB
authors.lastname: Corry
authors.affiliation: Department of Internal Medicine, University of Iowa, Iowa City, IA, United States.
authors.forename: Patricia L
authors.initials: PL
authors.lastname: Winokur
authors.affiliation: Gamble Program for Clinical Studies, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.
authors.forename: Rebecca C
authors.initials: RC
authors.lastname: Brady
authors.affiliation: Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, United States.
authors.forename: Wilbur H
authors.initials: WH
authors.lastname: Chen
authors.affiliation: Vanderbilt Vaccine Research Program, Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN, United States.
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Edwards
authors.affiliation: Vanderbilt Vaccine Research Program, Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN, United States.
authors.forename: C Buddy
authors.initials: CB
authors.lastname: Creech
authors.affiliation: Duke Clinical Vaccine Unit, Department of Pediatrics, Duke University School of Medicine, Durham, NC, United States.
authors.forename: Emmanuel B
authors.initials: EB
authors.lastname: Walter
authors.affiliation: Department of Internal Medicine, Saint Louis University School of Medicine, St. Louis, MO, United States.
authors.forename: Sharon E
authors.initials: SE
authors.lastname: Frey
authors.affiliation: Department of Internal Medicine, Saint Louis University School of Medicine, St. Louis, MO, United States.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Belshe
authors.affiliation: EMMES Corporation, Rockville, MD, United States.
authors.forename: Johannes B
authors.initials: JB
authors.lastname: Goll
authors.affiliation: EMMES Corporation, Rockville, MD, United States.
authors.forename: Heather
authors.initials: H
authors.lastname: Hill
authors.affiliation: Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, United States; Department of Medicine, Baylor College of Medicine, Houston, TX, United States.
authors.forename: Wendy A
authors.initials: WA
authors.lastname: Keitel
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000328:Adult; D000367:Age Factors; D000368:Aged; D016207:Cytokines / Q000276:immunology; D005260:Female; D053804:Granzymes / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular; D007117:Immunization, Secondary; D053124:Influenza A Virus, H5N1 Subtype; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000627:therapeutic use*; D007251:Influenza, Human / Q000517:prevention & control*; D007371:Interferon-gamma / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008297:Male; D008875:Middle Aged; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000627:therapeutic use; D055815:Young Adult
chemical_list: D000276:Adjuvants, Immunologic; D016207:Cytokines; C573415:IFNG protein, human; D007252:Influenza Vaccines; D015164:Vaccines, Inactivated; D007371:Interferon-gamma; D053804:Granzymes
keywords: Adjuvant; Cell mediated immune response; Cytokine; H5N1; Inactivated influenza vaccine