Vitamin D and allergic rhinitis: A mini-review

Table 1 Immune response in normal vs allergic rhinitis individuals

Features	Normal immunity	Allergic rhinitis
Th cell balance	Balanced Th1/Th2	Th2 skewed dominance
IgE production	Low IgE levels	High IgE levels promoting hypersensitivity
Epithelial barrier	Strong, intact	Impaired, leaky barrier facilitates allergen entry
Inflammation	Controlled, self-limited	Chronic, persistent nasal inflammation
Mast cell activation	Minimal under normal conditions	Heightened activation and mediator release
Clinical outcome	No allergic symptoms	Sneezing, itching, rhinorrhea, congestion

IgE: Immunoglobulin E; Th: T-helper.