Related Experiment Video
Updated: Jun 28, 2026

Humanized Mediator Release Assay as a Read-Out for Allergen Potency
Published on: June 29, 2021
Allergen-sensitization increases mast-cell expression of the exocytotic proteins SNAP-23 and syntaxin 4, which are
E Salinas1, A Quintanar-Stephano, L E Córdova
1Department of Microbiology, Basic Science Center, Autonomous University of Aguascalientes, México. emsalin@correo.uaa.mx
Background:
Activation of mast cells (MCs) via aggregation of immunoglobulin E (IgE) bound to its high affinity receptor (FcepsilonRI) results in release of inflammatory mediators from secretory granules. Histamine is one of the critical biological mediators released in the allergic response. Synaptosomal-associated protein of 23 kDa (SNAP-23) and syntaxin 4 are plasma membrane proteins that have been associated with exocytosis in MCs. Studies with monoclonal IgEs indicate that binding of IgE to FcepsilonRI induces molecular and biological changes in
Objectives:
The aim of this study was to investigate changes in the expression of SNAP-23 and syntaxin 4 by MCs following rat sensitization with ovalbumin (OVA). In addition, we assessed whether these proteins were involved in histamine secretion.
Methods:
SNAP-23 and syntaxin 4 expression was analyzed by Western blot using MCs from control and sensitized animals. Successful sensitization was confirmed based on the passive cutaneous anaphylaxis reaction. To test the role of these exocytotic proteins in histamine secretion, permeabilized MCs were incubated with SNAP-23 and syntaxin 4 antibodies.
Results:
Expression of SNAP-23 and syntaxin 4 was significantly higher in MCs from OVA-sensitized rats than in cells from control animals. In addition, incubation of permabilized cells with antibodies to SNAP-23 and syntaxin 4 led to a marked reduction of histamine secretion in stimulated cells.
Conclusions:
Sensitization with OVA increases the expression of SNAP-23 and syntaxin 4 in MCs. Furthermore, our data suggest that these exocytotic proteins participate in histamine secretion.
Related Concept Videos
Allergic Reactions
Allergic Reactions: Anaphylaxis
Hypersensitivities
Types of Hypersensitivities
Hypersensitivity reactions are categorized into four types: Type 1, Type 2, Type 3, and Type 4. Each type has a distinct mechanism...
Antibody Structure
Antibodies, also known as immunoglobulins (Ig), are essential players of the adaptive immune system. These antigen-binding proteins are produced by B cells and make up 20 percent of the total blood plasma by weight. In mammals, antibodies fall into five different classes, which each elicits a different biological response upon antigen binding.
The Y-Shaped Structure of Antibodies Consists of Four Polypeptide Chains
Antibodies consist of four polypeptide chains: two identical heavy...
Asthma-II: Pathophysiology and Classification
Additionally, environmental and genetic factors play crucial roles in determining an individual's susceptibility to asthma and the severity of their condition.
Critical processes in asthma pathophysiology include:
Allergic Drug Reactions

