What are the primary mechanisms of allergic rhinitis?

The primary mechanisms of allergic rhinitis involve a two-phase immune response: the early phase and the late phase. During the early phase, exposure to an allergen leads to the activation of mast cells, which release mediators such as histamine, prostaglandins, and leukotrienes. These mediators are responsible for the immediate symptoms of allergic rhinitis, such as sneezing, itching, and nasal congestion.

Following this early response, the late phase occurs several hours later and is characterized by the recruitment of other immune cells, particularly eosinophils, to the site of allergen exposure. Eosinophils are important for sustaining and amplifying the inflammatory response, leading to more prolonged symptoms.

This two-step mechanism—represented by early-phase mast cell secretion and late-phase eosinophil chemotaxis—illustrates how allergic rhinitis manifests initially with immediate reactions and then with more chronic symptoms due to ongoing inflammation. Therefore, the correct choice highlights the importance of both mast cells in the early response and eosinophils in the later phase of the allergic reaction.