allergen is the type of antigen that triggers an allergic reaction.
allergen is the type of antigen that triggers an allergic reaction.
type of antigen that triggers an allergic reaction?
allergen
the early phase of the allergic reaction typically occurs within minutes, or even seconds, following allergen exposure and is also commonly referred to as the immediate allergic reaction or as a type i allergic reaction. the reaction is caused by the release of histamine and mast cell granule proteins by a process called degranulation, as well as the production of leukotrienes, prostaglandins and cytokines, by mast cells following the cross-linking of allergen specific ige molecules bound to mast cell fcεri receptors. these mediators affect nerve cells causing itching, smooth muscle cells causing contraction (leading to the airway narrowing seen in allergic asthma), goblet cells causing mucus production, and endothelial cells causing vasodilatation and edema.
allergic inflammation
serum, suspected to contain ige antibodies, is drawn from the allergic (atopic) patient. this serum is injected intradermally into a non-allergic person. the suspected antigens are then intradermally injected into the non-allergic person 24–48 hours later. if the person being tested for an allergy has made antibodies for the antigen, this will cause a local reaction in the non-allergic person when the antibodies mix with the antigen. this demonstrates a type i hypersensitivity reaction, and the allergic reaction to the injected antigen is confirmed for the patient being tested. a positive pk test usually appears as a wheal and flare.
prausnitz–küstner test