Skip to main content

Allergic Rhinitis- How it occurs?

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.

Mechanism of Allergic Rhinitis

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.
  • Degranulation: Activated mast cells release pre-formed chemical mediators.
  • Primary Mediators:
    • Histamine: Causes itching, sneezing, vasodilation, nasal congestion, and rhinorrhea.
    • Proteases: Damage tissue structures and increase mucus secretion.
    • Leukotrienes & Prostaglandins: Cause prolonged smooth muscle contraction and fluid leakage.

3. Late-Phase Response (4–8 Hours Later)

  • Cytokine Release: Cytokines recruit inflammatory cells to the nasal mucosa.
  • Cellular Infiltration: Eosinophils, neutrophils, basophils, and T-cells migrate into nasal tissue.
  • Eosinophil Activation: Release of cytotoxic proteins causes prolonged inflammation and chronic nasal blockage.
Clinical Summary: The early phase is dominated by mast-cell histamine release, producing immediate symptoms. The late phase is driven by eosinophilic inflammation, resulting in persistent nasal congestion.

Reference:

https://www.mdpi.com/2227-9059/10/10/2486

Disclaimer: This content is for educational purposes only and is not a substitute for professional medical advice.

Reviewed by: Pharma / Healthcare Professional

Comments

Post a Comment

Popular posts from this blog

What is Phosphodiesterase 4 (PDE4)?

  Phosphodiesterase 4 (PDE4) is an enzyme that breaks down cyclic adenosine monophosphate (cAMP). cAMP is a signalling molecule that is involved in many cellular processes, including inflammation, pain, and smooth muscle contraction. PDE4 is expressed in a variety of tissues, including the lungs, skin, immune cells, and brain. The different PDE4 subtypes have distinct tissue distributions and functions. The main functions of PDE4 include: Regulating inflammation: PDE4 inhibitors are being studied as potential treatments for inflammatory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and rheumatoid arthritis. Regulating pain: PDE4 inhibitors are also being studied as potential treatments for pain conditions such as migraine and chronic pain. Regulating smooth muscle contraction: PDE4 inhibitors are being studied as potential treatments for conditions that involve smooth muscle contraction, such as asthma and urinary incontinence. Regulating cell growth and di...
Post a Comment
Read more

lipoma

What is lipoma ? A lipoma is a slow-growing, fatty lump that's most often situated between your skin and the underlying muscle layer. A lipoma, which feels doughy and usually isn't tender, moves readily with slight finger pressure. Lipomas are usually detected in middle age. Some people have more than one lipoma. A lipoma isn't cancer and usually is harmless. Treatment generally isn't necessary, but if the lipoma bothers you, is painful or is growing, you may want to have it removed. For example : For better understanding following images are showing the multiple lipoma on hand and abdomen wall.  Symptoms of a Lipoma The primary characteristics of a lipoma include: Soft and Doughy: They are soft to the touch and have a rubbery consistency. Movable: They are not fixed to the underlying tissue and move easily under the skin when touched. Small Size: They are typically less than 2 inches (5 cm) in diameter, though some can grow larger. Painless: Most lipoma...
Post a Comment
Read more