Which mediators are immediately released in the pathogenesis of allergic rhinitis (hay fever)?

Updated: Dec 26, 2018
  • Author: Javed Sheikh, MD; Chief Editor: Michael A Kaliner, MD  more...
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Answer

The mediators that are immediately released include histamine, tryptase, chymase, kinins, and heparin. [8, 9] The mast cells quickly synthesize other mediators, including leukotrienes and prostaglandin D2. [10, 11, 12] These mediators, via various interactions, ultimately lead to the symptoms of rhinorrhea (ie, nasal congestion, sneezing, itching, redness, tearing, swelling, ear pressure, postnasal drip). Mucous glands are stimulated, leading to increased secretions. Vascular permeability is increased, leading to plasma exudation. Vasodilation occurs, leading to congestion and pressure. Sensory nerves are stimulated, leading to sneezing and itching. All of these events can occur in minutes; hence, this reaction is called the early, or immediate, phase of the reaction.

Over 4-8 hours, these mediators, through a complex interplay of events, lead to the recruitment of other inflammatory cells to the mucosa, such as neutrophils, eosinophils, lymphocytes, and macrophages. [13] This results in continued inflammation, termed the late-phase response. The symptoms of the late-phase response are similar to those of the early phase, but less sneezing and itching and more congestion and mucus production tend to occur. [13] The late phase may persist for hours or days.


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