Definition

Noun: 1. A type of antibody: Specifically, reagin is an immunoglobulin of the IgE class. It is produced by the immune system in response to an allergen (e.g., pollen, dust mites, certain foods). 2. Function in allergic reactions: This antibody attaches to the surface of mast cells and basophils. Upon re-exposure to the specific allergen, it triggers these cells to release histamine and other chemicals, causing the symptoms of an immediate hypersensitivity (allergic) reaction.

Usage Examples

• Noun:
  • The skin test showed a strong reaction, indicating the presence of reagin to cat dander.
  • Scientists measured the level of specific reagin in the patient's blood to confirm the peanut allergy.
  • The release of histamine, initiated by reagin, leads to inflammation and itching.

Advanced Usage

• Reaginic antibody: This is a more technical synonym for reagin, explicitly stating it is an antibody with reagin-like activity.
  • The test detects reaginic antibodies in the serum.
• In historical medical contexts, "reagin" was also used to refer to antibodies involved in the Wassermann test for syphilis. In modern immunology, the term is almost exclusively associated with IgE and allergic responses.

Variants and Related Words

• Reaginic (adjective): Describing something related to or of the nature of reagin.
  • The patient exhibited a reaginic response to the antigen.

Synonyms

• IgE antibody
• Reaginic antibody
• Sensitizing antibody (in the context of allergy)

Notes on Meaning

The primary and modern meaning of "reagin" is the IgE antibody responsible for common allergic reactions (e.g., hay fever, asthma, anaphylaxis). Its historical use in syphilis serology is largely obsolete in contemporary language.

Noun

1. an immunoglobulin E that is formed as an antibody against allergens (such as pollen); attaches to cell membranes causing the release of histamine and other substances responsible for the local inflammation characteristic of an allergy