Related Experiment Video
Updated: Jan 7, 2026
Experimental Human Pneumococcal Carriage
Published on: February 15, 2013
Relationship between IL-17_A and pneumococcal carriage in children aged under two years: data from a randomised
Zheng Quan Toh1, Yi Ying Ma1, Beth Temple2
1Infection, Immunity and Global Health, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia; Department of Paediatrics, The University of Melbourne, Parkville, Victoria, Australia.
Insights
Pneumococcal carriage in young children is linked to elevated levels of Interleukin-17A (IL-17A) and related cytokines. These findings suggest a role for IL-17A in pneumococcal carriage, but not its clearance in this age group.
Area of Science:
- Immunology
- Pediatrics
- Microbiology
Background:
- Pneumococcal carriage precedes invasive pneumococcal disease (IPD).
- Interleukin-17A (IL-17A) and IL-17A-producing cells are implicated in pneumococcal carriage clearance in adults.
- The role of IL-17A in pediatric pneumococcal carriage remains unclear.
Purpose of the Study:
- To investigate the association between IL-17A, related cytokines (IL-22, IL-23, IFNγ), and IL-17A-producing cells with pneumococcal carriage in children under two years old.
- To explore the relationship between these immune markers and the number of pneumococcal serotypes carried.
Main Methods:
- Analysis of blood samples from 143 unvaccinated children at 18 months and nasopharyngeal swabs from birth to 24 months.
- Measurement of plasma cytokine concentrations (IL-17A, IL-22, IL-23, IFNγ) using multiplex bead array or ELISA.
- Quantification of IL-17A/IFNγ-producing cells via flow cytometry on peripheral blood mononuclear cells.
Main Results:
- Higher plasma concentrations of IL-17A, IL-22, IL-23, and IFNγ were observed in pneumococcal carriers compared to non-carriers at 18 months.
- Children carrying two or more pneumococcal serotypes exhibited significantly higher IL-17A, IL-22, and IL-23 levels.
- No difference in IL-17A-producing cells was found between carriers and non-carriers; these cytokines did not predict pneumococcal clearance at 24 months.
Conclusions:
- Pneumococcal carriage in children under two years is associated with elevated plasma IL-17A, IL-22, and IL-23 concentrations.
- While associated with carriage, IL-17A and related cytokines do not appear to influence pneumococcal clearance in this age group.
Objective:
Pneumococcal carriage is a prerequisite for invasive pneumococcal disease (IPD). Interleukin (IL)-17 A and IL-17 A-producing cells are involved in the clearance of pneumococcal carriage in adults, but their role in children is unclear. This study aims to examine the relationship between IL-17 A, IL-17 A-related cytokines (IL-22, IL-23, IFNγ) and IL-17 A-producing cells and pneumococcal carriage in children aged under two years.
Methods:
Blood samples (n = 143) collected from unvaccinated children at 18 months (m) of age and nasopharyngeal swabs collected from unvaccinated children at 2, 6, 9, 12, 18, 24 m in the Vietnam Pneumococcal Project (ClinicalTrials.gov, NCT01953510) were included in this analysis. Pneumococcal carriage was previously determined. Plasma cytokine concentrations were measured by multiplex bead array or ELISA. Flow cytometry was used to measure IL-17 A/IFNγ-producing cells in peripheral blood mononuclear cells.
Results:
IL-17 A, IL-22, IL-23 and IFNγ plasma cytokine concentrations were 1.7 to 2.6-fold higher among pneumococcal carriers at 18 m of age compared with non-carriers. Two-to four-fold higher IL-17 A, IL-22, IL-23 concentrations were observed in children carrying two or more pneumococcal serotypes at 18 m compared with children who only carried one pneumococcal serotype or non-carriers. Pneumococcal carriers at 18 m of age had 1.6 to 2-fold higher IL-17 A, IL-22, IL-23 compared with carriers at earlier timepoints (≤12 m). No differences in the frequencies of IL-17 A-producing cells were observed between carriers and non-carriers at 18 m of age. IL-17 A and related cytokines at 18 m of age did not appear to influence clearance of pneumococcus at 24 m of age.
Conclusion:
Pneumococcal carriage is associated with higher plasma IL-17 A, IL-22 and IL-23 concentrations in children aged under two years.
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