CD4+ T-cell immunity after pandemic influenza vaccination cross-reacts with seasonal antigens and functionally differs from active influenza infection

Eur J Immunol. 2012 Jul;42(7):1755-66. doi: 10.1002/eji.201242393.

Abstract

Antigen-specific antibodies are well characterized after vaccination with pandemic H1N1 or seasonal influenza vaccines. However, knowledge on cellular immunity toward pandemic H1N1 after vaccination and infection and cross-reactivities toward seasonal antigens is limited. Nineteen individuals were vaccinated with the pandemic H1N1 vaccine. Among those, ten had been prevaccinated against seasonal influenza. CD4(+) T cells specific for pandemic H1N1 and for seasonal vaccine, and antibodies were monitored using flow cytometry and ELISA/neutralization assays, respectively. In addition, seven patients with acute pandemic influenza infection were analyzed. Pandemic H1N1 vaccination induced a strong 4.63-fold (IQR 4.16) increase in antigen-specific CD4(+) T cells that was more pronounced in individuals not prevaccinated with seasonal influenza (p = 0.01). T-cell levels toward seasonal vaccine concomitantly rose by 2.71-fold (IQR 2.26). Likewise, prevaccination with seasonal influenza induced a less pronounced increase in specific antibodies. Influenza-specific T cells in vaccinees had a Th1 phenotype mainly coexpressing IFN-γ and IL-2, whereas patients with active pandemic influenza showed a shift toward cells predominantly expressing IFN-γ. In conclusion, T cells toward seasonal influenza antigens cross-react with pandemic H1N1 antigens and affect induction of specific T cells after pandemic influenza vaccination. In addition, the cytokine patterns of specific T cells during acute H1N1 infection and after vaccination differ, and the predominantly dual-positive cytokine profile of vaccine-induced T cells suggests sufficient functionality to confer successful virus control.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antibodies, Viral / blood
  • CD4-Positive T-Lymphocytes / immunology*
  • Cross Reactions / immunology
  • Enzyme-Linked Immunosorbent Assay
  • Flow Cytometry
  • Humans
  • Immunity, Cellular / immunology
  • Influenza A Virus, H1N1 Subtype / immunology*
  • Influenza Vaccines / administration & dosage*
  • Influenza Vaccines / immunology*
  • Influenza, Human / epidemiology
  • Influenza, Human / immunology*
  • Influenza, Human / prevention & control
  • Influenza, Human / virology
  • Interferon-gamma / blood
  • Interleukin-2 / blood
  • Middle Aged
  • Neutralization Tests
  • Pandemics / prevention & control*
  • Statistics, Nonparametric

Substances

  • Antibodies, Viral
  • Influenza Vaccines
  • Interleukin-2
  • Interferon-gamma