Vitamin D Increases Percentages of Interleukin-10 Secreting Regulatory T Cells in Children with Cow's Milk Allergy.

Cow's milk allergy (CMA) is known to be either IgE- or non-IgE mediated. Regulatory T (Treg) cell defect is involved in the pathogenesis of both types. Vitamin D has been suggested to improve the generation of allergen-specific Treg cell populations with the potential to provide safe and long-term alleviation of disease symptoms. This study aimed to assess Vitamin D status in children with physician-diagnosed CMA and to investigate the effect of in vitro cultivation with Vitamin D on the percentage of antigen-driven CD4+CD25highFoxp3+IL10+ Treg cells following in vitro stimulation of cells with cow's milk allergen in culture. This cross-sectional study included 20 children with CMA and 20 healthy age and sex-matched children as a control group. All patients were subjected to clinical evaluation, cow's milk skin prick test (SPT), cow's milk elimination and oral re-challenge test in patients with negative cow's milk SPT and in those with gastrointestinal presentation, measurement of serum Vitamin D level and assessment of the percentage of antigen-driven CD4+CD25highFoxp3+IL10+ Treg cells in response to stimulation with cow's milk allergen extract with and without Vitamin D in culture. Vitamin D deficiency was detected in 80% of children with CMA. Percentage of Foxp3+ and IL10+ co-expression on Treg cells was significantly increased after stimulation with cow's milk allergen extract in the presence of Vitamin D. A significant positive correlation was observed between serum Vitamin D level and percentage of antigen-driven CD4+CD25highFoxp3+IL10+ Treg cells as well as level of Foxp3+ and IL10+ co-expression on Treg cells at baseline (control cultures without stimulation) and after PBMCs stimulation with cow's milk allergen extract in the presence of Vitamin D. Re-stimulation with cow's milk allergen extract was performed in vitro in order to evaluate milk-induced immune stimulation and regulation. In conclusion, patients with CMA whether IgE- or non-IgE mediated had Vitamin D deficiency with a decreased number of CD4+CD25highFoxp3+IL10+ Treg cells which increased after in vitro addition of Vitamin D with increased Foxp3 and IL10 co-expression.