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Adaptive Immunity against Streptococcus pyogenes in Adults Involves Increased IFN-γ and IgG3 Responses Compared with

Rasmus Mortensen1, Thomas Nørrelykke Nissen2, Thomas Blauenfeldt3

  • 1Department of Infectious Disease Immunology, Statens Serum Institut, DK-2300 Copenhagen S, Denmark; Department of Immunology and Microbiology, University of Copenhagen, DK-2200 Copenhagen N, Denmark; and jdi@ssi.dk rjm@ssi.dk.

Journal of Immunology (Baltimore, Md. : 1950)
|July 12, 2015
PubMed

Insights

Millions infected with Streptococcus pyogenes annually. This study details the adaptive immune response in children and adults, finding robust Th1 and IgG1/IgG3 immunity that increases with age, potentially explaining infection rates.

Area of Science:

  • Immunology
  • Microbiology
  • Pediatrics

Background:

  • Streptococcus pyogenes (group A Streptococcus) causes millions of infections and 500,000 deaths yearly.
  • School-aged children exhibit higher Streptococcus pyogenes infection rates than adults for unclear reasons.

Purpose of the Study:

  • To characterize the human adaptive immune response to Streptococcus pyogenes in children and adults.
  • To investigate age-related differences in immunity against conserved group A streptococci antigens.

Main Methods:

  • Analysis of adaptive immune responses, including T-cell subsets and antibody isotypes.
  • Measurement of cytokine profiles (IFN-γ, IL-5, IL-13, IL-17, TNF-α) and IgG subclasses (IgG1, IgG3, IgG4).
  • Comparison of immune responses between pediatric and adult populations.

Main Results:

  • Adults and most children demonstrated immunity against streptococcal C5a peptidase and an immunogenic secreted protein.
  • Immune responses were dominated by Th1 T cells (TNF-α(+) and IL-2(+)TNF-α(+) subsets) and IgG1/IgG3 antibodies.
  • Children had lower levels of IgG3 and Interferon-gamma (IFN-γ) compared to adults, despite similar cytokine release patterns.

Conclusions:

  • Human adaptive immunity against Streptococcus pyogenes involves a strong Th1 cellular memory response and age-dependent IgG1/IgG3 humoral immunity.
  • The observed age-related increase in immunity may contribute to understanding higher infection rates in children.
  • Findings offer insights for developing effective group A Streptococcus vaccines.

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