Regulatory T cells in early life: comparative study of CD4+CD25high T cells from foals and adult horses.
Authors: Hamza Eman, Mirkovitch Jelena, Steinbach Falko, Marti Eliane
Journal: PloS one
Summary
# Editorial Summary: Regulatory T Cell Development in Foals The maturation of immune tolerance during early life sets the foundation for lifelong health, yet longitudinal immune studies remain difficult in humans for both ethical and practical reasons—making horses an invaluable model for understanding how regulatory T cells (Tregs) develop and influence conditions like insect bite hypersensitivity. Researchers compared circulating CD4+CD25highFoxP3+ Treg cells between 19 foals (aged 1–5 months), their dams, and six yearlings, measuring both the proportion of these cells in circulation and their suppressive capacity, whilst also testing whether foal-derived cells could be induced from naive precursors in vitro. Foals demonstrated a substantially higher proportion of FoxP3+ cells within the CD4+CD25high population (47%) relative to both adult mares (18%) and yearlings (26%), alongside superior suppressive function; notably, foal CD4+CD25high cells could be induced from CD4+CD25− precursors at significantly higher rates than those from adult horses, and these induced cells showed enhanced regulatory capacity. These findings suggest that early allergen exposure during the critical window of immune maturation may promote the establishment of induced Treg-mediated tolerance, which has implications for understanding why horses exposed to insect allergens later in life show increased IBH incidence, and potentially for informing management strategies around grazing and environmental exposure in young stock.
Read the full abstract on PubMed
Practical Takeaways
- •Early allergen exposure in foals during immune system maturation may help establish tolerance and reduce risk of developing insect bite hypersensitivity later in life
- •The developing immune system in foals has greater capacity to generate and induce regulatory T cells, suggesting a critical window for tolerance development
- •Understanding foal immune competency may inform management strategies for allergy prevention, potentially through controlled early exposure to common allergens
Key Findings
- •Foals have significantly higher proportions of FoxP3+ regulatory T cells (47%) in circulating CD4+CD25high population compared to adult mares (18%) and yearlings (26%)
- •Regulatory T cells from foals display higher suppressive capability than those from adult horses
- •CD4+CD25high cells can be induced in vitro from CD4+CD25- cells at significantly higher proportions in foals compared to mares, with enhanced suppressive function