Objectives:

This study aims to investigate the efficacy, safety, and T regulatory cell response of vitamin D supplementation concomitantly used with allergen specific immunotherapy (SIT).

Materials and methods:

Fifty children (29 girls, 21 boys; mean age 8.8±2.4 years) with asthma sensitized to house dust mite receiving pharmacotherapy were randomized into three groups as: subcutaneous immunotherapy in combination with vitamin D supplementation group (650 U/day; n=17), subcutaneous immunotherapy group (n=15) and pharmacotherapy group (n=18). All patients were evaluated at baseline, 6 and 12 months for the symptom frequency, medication need, skin prick test, levels of serum vitamin D, total immunoglobulin E (IgE), specific IgE, and Der p 1-specific IgG4 levels. Dermatophagoides pteronyssinus induced CD4⁺CD25⁺Foxp3⁺ T regulatory cell ratio, intracellular Foxp3 expression, and peripheral blood mononuclear cell interleukin 10 (IL-10) and transforming growth factor beta responses were assessed.

Results:

Concomitant use of vitamin D as an adjunct to allergen SIT reduced asthma symptoms compared to the others at six months. The need for corticosteroids also decreased, compared to the pharmacotherapy group. The baseline vitamin D levels were inversely correlated with the asthma attack number of the subsequent year. At one year, vitamin D supplemented subjects demonstrated a higher percentage of Der p 1-induced CD4⁺CD25⁺Foxp3⁺ regulatory T cell ratio and IL-10 levels in lymphocytes, compared to other groups. Der p 1-specific IgG4 increased in both SIT groups and the increase was observed as an earlier surge at six months in vitamin D supplemented group.

Conclusion:

Concomitant use of SIT and vitamin D improved asthma control and reduced the inhaled corticosteroid need at an earlier stage. This beneficial clinical effects were accompanied by an increased ratio of Der p 1-induced T regulatory cells and expression of Foxp3.

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