🚨 IgE-Mediated Mast Cell Degranulation Simulator

Prior Sensitization: IgE Coats the Mast Cell Surface

First allergen exposure primes IgE onto FcεRI receptors.

• FcεRI: Receptor (high-affinity IgE receptor)
• ~500k: IgE per cell (placeholder estimate)
• 1st contact: Priming exposure (no symptoms yet)
• Mast cell: Cell type (tissue-resident sentinel)

IgE production and receptor loading

Placeholder: B cells class-switch to IgE against the allergen.

Surface receptor saturation

Placeholder: FcεRI becomes densely coated with specific IgE.

Allergen Re-Exposure Cross-Links Surface IgE

Multivalent allergen bridges two or more adjacent IgE molecules.

• Re-exposure: Trigger (same allergen returns)
• 2 IgE: Min. bridge (placeholder threshold)
• Fab region: Binding site (allergen epitope contact)
• Seconds: Onset (placeholder timescale)

Multivalent allergen bridging

Placeholder: allergen epitopes span and link neighboring IgE-Fc complexes.

Receptor clustering

Placeholder: cross-linked receptors aggregate into signaling clusters.

Cross-Linking Triggers the Degranulation Cascade

Clustered receptors activate kinases and calcium signaling inside.

• Lyn/Syk: Kinase (placeholder signaling axis)
• Ca²⁺ influx: Second messenger (placeholder trigger)
• <1 min: Latency (placeholder estimate)
• Granule fusion: Outcome (commits to release)

Intracellular signal cascade

Placeholder: kinase activation propagates from receptor to granules.

Calcium-driven commitment

Placeholder: calcium flux commits granules to membrane fusion.

Granule Fusion Releases Histamine, Tryptase, Leukotrienes

Stored and newly made mediators burst out of the cell.

• Histamine: Preformed (stored in granules)
• Tryptase: Preformed (protease granule content)
• Leukotrienes: Newly made (lipid mediators, de novo)
• Exocytosis: Process (placeholder mechanism)

Preformed granule contents

Placeholder: histamine and tryptase are pre-packaged for instant release.

De novo lipid mediators

Placeholder: leukotrienes are synthesized rapidly after activation.

Mediators Spread Into Systemic Anaphylaxis

Circulating mediators cause vasodilation, edema, and bronchoconstriction.

• Vasodilation: Vessels (placeholder effect)
• Bronchoconstriction: Airway (placeholder effect)
• Urticaria: Skin (placeholder effect)
• Anaphylactic shock: Worst case (placeholder severity)

Vascular and airway effects

Placeholder: mediators act on distant vessels and smooth muscle.

Clinical progression

Placeholder: symptoms escalate from mild to systemic shock.

Placeholder: epinephrine reverses the cascade in emergency treatment.