Cell mediated immune responses following revaccination with an influenza A/H5N1 vaccine

Vaccine. 2016 Jan 20;34(4):547-554. doi: 10.1016/j.vaccine.2015.11.055. Epub 2015 Dec 4.


Purpose: 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.

Conclusion: CMI responses occur in adults administered influenza A/H5N1 inactivated influenza vaccine.

Keywords: Adjuvant; Cell mediated immune response; Cytokine; H5N1; Inactivated influenza vaccine.

Publication types

  • Clinical Trial, Phase I
  • Clinical Trial, Phase II
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adjuvants, Immunologic / administration & dosage
  • Adult
  • Age Factors
  • Aged
  • Cytokines / immunology
  • Female
  • Granzymes / immunology
  • Humans
  • Immunity, Cellular*
  • Immunization, Secondary*
  • Influenza A Virus, H5N1 Subtype
  • Influenza Vaccines / administration & dosage*
  • Influenza Vaccines / therapeutic use*
  • Influenza, Human / prevention & control*
  • Interferon-gamma / immunology
  • Leukocytes, Mononuclear / immunology
  • Male
  • Middle Aged
  • Vaccines, Inactivated / administration & dosage
  • Vaccines, Inactivated / therapeutic use
  • Young Adult


  • Adjuvants, Immunologic
  • Cytokines
  • IFNG protein, human
  • Influenza Vaccines
  • Vaccines, Inactivated
  • Interferon-gamma
  • Granzymes