Database of 2329 Experimentally Validated Allergens

Experimental Validation of Allergens

In simple terms, an allergic reaction is characterized by binding of the allergen to IgE and development of symptoms in a sensitized individual. Experimental characterization of an allergen is very critical to accurately assess its allergenicity and immunological features. Several in vivo and in vitro methods (assays) are employed for this purpose.

AllerBase archives data on experimental characterization of allergens which is represented by the tests/methods used for allergen characterization accompanied with their respective references. These methods/assays are grouped into four categories: (a) IgE assays/tests which comprise of IgE antibody-based assays (b) Biological tests/assays which act as important diagnostic tools for allergy (c) Physicochemical tests employed for allergen characterization and (d) Cell -based assay which study effects of allergen on specific cells.

Each reference is represented either by its PubMed ID or the Digital Object Identifier (DOI) with cross-link to the journal page. The complete list of references along with corresponding details of the assay/test for each allergen is provided on separate pages. The user has the option of selecting and downloading the abstracts using the toggle buttons provided.

Data for 10 IgE assays/tests, 7 biological assays/tests, 4 physicochemical tests and 1 cell-based assay are documented in AllerBase, as per availability, for each allergen. Following are the experimental methods (assays) enlisted in AllerBase.

Biological assays/tests:

Basophil/Mast cell/Histamine Test:

It includes methods like Mast cell degranulation assay, Basophil Activation Test (BAT), and Histamine release assay. These methods represent IgE-independent assay that are used to assess clinical effects in vitro or in vivo.

Bronchial Test:

Bronchial provocation test (bronchial challenge) is a test used to evaluate bronchial hyperresponsiveness of an allergen and it plays an important role in diagnosis of allergic diseases like asthma.

Conjunctival Test:

Conjunctival provocation test is used to detect the ocular response to allergens and diagnosis of allergic diseases like allergic conjunctivitis.

Nasal Test:

Nasal provocation test is used to detect allergic response from the nasal mucosa and diagnosis of diseases like allergic rhinitis.

Oral Test:

Oral food test or Oral food challenge is a test to study allergic response to food allergens and evaluate oral allergy syndrome.

Passive cutaneous anaphylaxis (PCA):

Passive cutaneous anaphylaxis (PCA) is a kind of skin test to assess allergic reactions. The assay involves in vivo passive transfer of antibodies and detection of allergen-antibody interaction responsible for mediating allergic reactions.

Skin Test:

Skin prick test (SPT) is a rapid and reliable test employed to detect sensitization to allergens and the diagnosis of immediate-type allergic reactions.

IgE Assays/Tests:

EAST:

Enzyme-allergosorbent assay (EAST) is a type of enzyme immunoassay used to assess allergenicity by quantification of total and allergen-specific antibodies.

ELISA:

ELISA (enzyme-linked immunosorbent assay) is a very efficient assay for qualitative and quantitative analysis of allergen-antibody interaction. The technique is routinely used for to characterize allergenicity by detecting and quantifying allergen-specific antibodies.

Crossed immunoelectrophoresis:

Crossed immunoelectrophoresis, also known as two-dimensional (2-D) immunoelectrophoresis is a useful older method which was used to detect and identify allergens in allergic extracts based on their interactions with specific antibodies.

Fluorescence Immunoassay:

Fluorescence Immunoassay (FIA) is a very sensitive immunoassay technique used to detect interaction of allergens with specific antibodies. The main feature of the assay is the detection system based on a fluorescent compound which absorbs light or energy at a specific wavelength and then emits light or energy at a different wavelength.

Immunochemiluminescent assay:

Immunochemiluminescent assay is a sensitive and rapid method to identify allergen- antibody binding, which is dependent on chemiluminescence-based detection system.

ImmunoCAP Test:

ImmunoCAP specific IgE test is a recent advanced assay for in vitro diagnosis of allergy. The method is extremely accurate and detects allergen-specific antibodies present in very small quantities.

Microarray:

It is a widely used assay for efficient characterization of allergenicity by detecting allergen- antibody binding. Major advantage of microarray technique is the high throughput approach which results in analysis of several allergens simultaneously.

Radio Immunoassay:

Radioimmunoassay (RIA) is a very sensitive and widely employed immunoassay for characterization of allergenicity. The assay can be used both as a qualitative and quantitative measure of allergen antibody binding.

RAST:

Radioallergosorbent test (RAST) is a type of radioimmunoassay that is specifically used to characterize allergenicity. The assay is able to detect binding of allergens with specific antibodies, which indicates the measure of allergenicity.

Western/Immunoblot:

Immunoblot (Western blot) is the most extensively used assay for characterization of allergenicity. It is employed to accurately detect the allergen-antibody binding and can be used as qualitative or quantitative assay. Separation of allergenic proteins by using electrophoresis techniques followed by analysis of antibody binding by blotting is the most common method of allergen characterization.

Physicochemical Tests:

Chromatography:

It is a very commonly used method for purification and physicochemical characterization of allergens. Chromatographic techniques like affinity chromatography and HPLC (High Performance Liquid Chromatography) have been increasingly used in recent years.

Isoelectrofocusing:

Isoelectric focusing (IEF) is a less frequently used technique for identification of allergens. The method is predominantly employed for separation of allergens from complex extracts.

Mass spectrometry (MS):

Mass spectrometry is major proteomic technique that has been frequently used for identification and characterization of allergens. MS-based characterization either targets the allergen itself or an important region of it (e.g. N-terminal sequence)

N-terminal sequencing/sequence analysis:

It is routinely employed method for unambiguous identification and characterization of allergens.

Cell-based Assay:

Lymphocyte proliferation assay:

The lymphocyte proliferation assay is used assess cell mediated response to an allergen in vitro. It detects proliferation of T-cells or peripheral blood mononuclear cells (PBMCs), which play important roles in allergic reactions.