Breast milk interleukin-7 and thymic gland development in infancy

  • Elham M. Hossny
  • Dalia H. El-Ghoneimy
  • Rasha H. El-OwaidyEmail author
  • Mohamed G. Mansour
  • Mohammad T. Hamza
  • Amira F. El-Said
Original Contribution



Interleukin-7 (IL-7) is known to be important for lymphocyte development. We sought to investigate the maternal breast milk IL-7 expression to explore its impact on thymus development in infants.


We conducted a prospective study on three groups of healthy infants classified into exclusively breast-fed (n = 19), formula-fed (n = 17) and mixed-fed (n = 19) infants. They were investigated at 2, 4 and 6 months of age for thymic indices by ultrasonography, T lymphocyte subsets enumeration by flowcytometry and breast milk IL-7 levels.


Thymic indices were higher at the age of 2 and 6 months in the exclusively breast-fed infants (mean ± SD 22.4 ± 2.1, 26.2 ± 2.7 mm3, respectively) and mixed-fed infants (mean ± SD 22 ± 3.2, 25 ± 3.2, respectively) as compared to formula-fed infants (mean ± SD 17.9 ± 3.7, 21.6 ± 3.9 respectively); p < 0.001. In the exclusively breast-fed infants, IL-7 levels correlated positively to thymic indices and CD3+ T cell numbers at 2 months of age. Positive correlations were elicited in the mixed-fed group at 2, 4 and 6 months of age for thymic indices and at 6 months for CD3+ cells.


Breast milk and/or its IL-7 content have a significant positive impact on thymic development. Our conclusions are limited by the sample size and short duration of follow-up. What is known is that breast milk has a trophic role in thymic development and contains IL-7. What is new is that there is positive correlation between breast milk IL-7 concentration and thymic development and lymphocyte output; variation of IL-7 levels with type of feeding (exclusive breast feeding/mixed breast and formula feeding) and with time postnatally.


Breast milk Thymus IL-7 T-cells Immunity Infants 



Complete blood counting


Cluster of differentiation


Interleukin 7



This work was supported by the Ain Shams Faculty of Medicine Grants Office, Grant number: 2016/22. The funding source has no involvement in the study design; collection, analysis and interpretation of data; writing of the manuscript; or in the decision to submit the article for publication.

Author contributions

EH: Has put the study idea and design, supervised the whole work, contributed to the interpretation of the results and contributed to and revised the manuscript writing. DE, RE: supervised the clinical work and, contributed to implementation of the research and interpretation of the results and wrote the manuscript. AE: Carried out the clinical part, samples and data collection and statistical analysis. MGM: Carried out the radiological part of the work. MTH: Carried out the laboratory part of the work. All authors discussed the results and contributed to the final manuscript.


This work was supported by the Ain Shams Faculty of Medicine Grants Office, Grant number: 2016/22. The funding source has no involvement in the study design; collection, analysis and interpretation of data; writing of the manuscript; or in the decision to submit the article for publication.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Informed consent

An informed written consent was obtained from the mother for their and their infants’ participation in the study. The study has been approved by the Local Ethics Committee of the Department of Pediatrics, Ain shams university and the Research Ethics Committee of faculty of medicine, Ain shams university (approval number: FMASU 1606/2013).


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Elham M. Hossny
    • 1
  • Dalia H. El-Ghoneimy
    • 1
  • Rasha H. El-Owaidy
    • 1
    Email author
  • Mohamed G. Mansour
    • 2
  • Mohammad T. Hamza
    • 3
  • Amira F. El-Said
    • 1
  1. 1.Pediatric Allergy and Immunology Unit, Children’s HospitalAin Shams UniversityCairoEgypt
  2. 2.Radiology DepartmentAin Shams UniversityCairoEgypt
  3. 3.Clinical Pathology DepartmentAin Shams UniversityCairoEgypt

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