Allergic Rhinitis Causes & Mechanisms

Woman sneezing



The “allergic cascade” and its role in allergic rhinitis (AR)

Allergic cascade

The “allergic cascade” and its vital role in allergic rhinitis (AR)1

The body’s immune response to allergens includes a series of early- and late-phase reactions—the allergic cascade. There are several allergic mediators involved in this cascade, not histamines alone.3

Typically, the allergic cascade follows this pattern3:

  1. Exposure and sensitization to an allergen
  2. Early-phase response upon re-exposure to an allergen
  3. Late-phase response initiated by early-phase allergic mediators

When the body is exposed to an allergen:

  • Sensitization involves being exposed to an allergen for the first time3
  • The body produces immunoglobulin E (IgE) in response to the allergen, but an allergic reaction/symptoms does not yet occur3
  • Re-exposure to an allergen triggers an early-phase response that typically occurs within minutes3
  • IgE bound to receptors on mast cells bind to the allergen, crosslinking the IgE3
  • When sufficient crosslinking occurs, the mast cells explode releasing histamine and many other inflammatory mediators, such as cytokines, leukotrienes, prostaglandins, eosinophils, and thromboxanes1,3
  • The late-phase response occurs from 6-12 hours after allergen re-exposure1
  • In this late-phase, immune cells, such as eosinophils, secrete substances that further promote the inflammatory response and recruit other immune cells into the reaction, perpetuating the inflammation and resulting symptoms1,3
  • The symptoms can be more severe and persistent than those in the early phase1,3

The end result is the allergic response consisting of a range of bothersome symptoms, often impacting patient quality-of-life, such as rhinorrhea (runny nose), sneezing, congestion, and pruritus (itching).1


In fact, 71% of AR patients suffer from either moderate or severe allergy symptoms.4

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