Allergic Rhinitis – How it occurs? Allergic rhinitis is an IgE-mediated inflammatory response of the nasal mucous membranes. It occurs after exposure to airborne allergens like pollen, dust mites, or animal dander. The biological mechanism follows a distinct multi-phase process. 1. Sensitization Phase (Initial Exposure) Allergen Entry: Airborne allergens enter the nasal cavity and pass through the mucosal epithelium. Antigen Presentation: Antigen-presenting cells process the allergen and present it to T-helper 2 (Th2) lymphocytes. Antibody Production: Th2 cells release cytokines (IL-4 and IL-13) stimulating B lymphocytes to produce allergen-specific IgE antibodies. Cell Binding: IgE antibodies bind to high-affinity receptors on mast cells and basophils, leading to sensitization. 2. Early-Phase Response (Minutes After Re-Exposure) Allergen Cross-linking: Re-exposure causes allergen binding to IgE on mast cells, activating them. ...