Vitamin D: immunomodulation of asthma, allergic rhinitis, and chronic rhinosinusitis.

PURPOSE OF REVIEW: To discuss the role of vitamin D in asthma, allergic rhinitis, and chronic rhinosinusitis (CRS). RECENT FINDINGS: Over the last several years, the role of vitamin D in immunomodulation has been studied and shown to have a significant impact on immune function. A causal relationship exists between vitamin D function and innate and adaptive immunity to infections. The mechanisms underlying vitamin D immune actions could be attributed to a paracrine feedback loop that reduces inflammation as well as influencing the differentiation fate of activated CD4 T cells, or the enhancement of suppressor T-cell function; indeed, a combination of these factors may underlie the actions of vitamin D. SUMMARY: Recent findings on the function of vitamin D may explain aspects of the pathophysiology of allergic rhinitis and CRS and may help direct future interventions and treatment of these diseases.