n. a type of *antibody, formed against an allergen, that has special affinity for cell membranes and remains fixed in various tissues. Subsequent contact with the allergen causes damage to the tissues when the antigen-antibody reaction occurs. The damaged cells, particularly *mast cells, release histamine and serotonin, which are responsible for the local inflammation of an allergy or the very severe effects of anaphylactic shock (see anaphylaxis). Reagins belong to the IgE class of *immunoglobulins.
As used by immunologists, this term refers to IgE antibodies. As used by microbiologists, it refers to antibodies produced in syphilis – probably in response to the tissue damage caused by Treponema pallidum. Production of these antibodies in patients with syphilis has been utilised in the development of the non-treponemal serological tests for syphilis such as the VDRL Test, the RPR Test and the now superceded Wasserman Complement Fixation Test. These tests are useful in that they are only positive in active syphilis but they have many biological false positive reactions, including pregnancy.... reaginic antibody
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