reagin

View more Health videos

1. An antibody found in the blood of individuals having a genetic predisposition to allergies such as asthma and hay fever.
2. A substance present in the blood of individuals having a positive serological test for syphilis.

1. a heat-labile antibody-like substance in the serum of many people suffering from atopic allergies, and identical with immunoglobulin E (IgE). The immediate hypersensitivity (type I) generated by the binding of IgE to its specific antigen on the surface of mast cells involves the release of cell mediators via the reaginic or anaphylactic mechanism.
2. a special kind of antibody response produced by syphilitics that has specificity for cardiolipin antigens.

An old term for immunoglobulin E antibody (IgE).

• atopic r. — the antibody responsible for hypersensitivity reactions to specific substances with signs of atopy resulting.

Noncommittal term used for antibodies or antibodylike substances that differ in several respects from ordinary antibodies. It refers to the antibodies of allergic conditions (atopy) and to the antibody (reagin) concerned with the flocculation and complement fixation tests for syphilis.