Is Infant Immunity Actively Suppressed or Immature?

Area of Science:

• Immunology
• Pediatric Infectious Diseases
• Cellular Immunology

Background:

• Millions of children under five die annually from vaccine-preventable infections.
• Young infants exhibit impaired immune responses to pathogens and vaccinations.
• Defects include reduced IL-12/IL-18 secretion by dendritic cells, poor T cell and NK cell function, and a Th2-biased T cell response.

Purpose of the Study:

• To investigate potential causes of infant immune deficiencies.
• To explore the role of active immune suppression in infant vulnerability.
• To identify novel therapeutic targets for enhancing infant immunity.

Main Methods:

• Review and contextualization of known immune suppressive pathways.
• Analysis of immune regulatory cells including mesenchymal stromal cells (MSC), myeloid-derived suppressor cells (MDSC), CD5+ B cells, and regulatory T cells (Tregs).
• Comparison of suppressed immune pathways with those defective in infants.

Main Results:

• Infant immune defects mirror pathways inhibited by regulatory immune cells.
• Mesenchymal stromal cells (MSC), myeloid-derived suppressor cells (MDSC), CD5+ B cells, and regulatory T cells (Tregs) actively suppress key immune functions.
• These suppressive mechanisms align with observed infant immune system immaturities.

Conclusions:

• Active suppression by regulatory immune cells may significantly contribute to infant immune deficiencies.
• This active suppression offers a novel perspective beyond immaturity and epigenetics.
• Targeting these suppressive pathways presents a promising avenue for therapeutic interventions in infants.