|immunol a type of antibody that is formed against an allergen and is attached to the cells of a tissue. The antigen--antibody reaction that occurs on subsequent contact with the allergen causes tissue damage, leading to the release of histamine and other substances responsible for an allergic reaction|
|[C20: from German reagieren to react + |
reagin re·a·gin (rē-ā'jĭn)
An antibody found in the blood of individuals having a genetic predisposition to allergies such as asthma and hay fever.
A substance present in the blood of individuals having a positive serological test for syphilis.