Thehigh-affinity IgE receptor, also known asFcεRI, orFc epsilon RI, is the high-affinityreceptor for theFc region ofimmunoglobulin E (IgE), anantibodyisotype involved inallergy disorders andparasite immunity. FcεRI is atetrameric receptor complex that binds Fc portion of the εheavy chain ofIgE.[1] It consists of one alpha (FcεRIα – antibody binding site), one beta (FcεRIβ – which amplifies the downstream signal), and two gamma chains (FcεRIγ – the site where the downstream signal initiates) connected by two disulfide bridges onmast cells andbasophils. It lacks the beta subunit on other cells. It is constitutively expressed on mast cells and basophils[2] and is inducible ineosinophils.
FcεRI was demonstrated in bronchial/tracheal airwaysmooth muscle cells in normal and asthmatic patients. FcεRI cross-linking by IgE and anti-IgE antibodies led to Th2 (IL-4, -5, and -13) cytokines and CCL11/eotaxin-1 chemokine release; and ([Ca2+]i) mobilization, suggesting a likely IgE-FcεRI-ASM (airwaysmooth muscle cell)-mediated link to airway inflammation andairway hyperresponsiveness.[7][8]
Crosslinking of the FcεRI via IgE-antigen complexes leads to degranulation of mast cells or basophils and release ofinflammatory mediators.[9] Under laboratory conditions,degranulation of isolated basophils can also be induced withantibodies to the FcεRIα, which crosslink the receptor. Such crosslinking and potentially pathogenicautoantibodies to the FcεRIα have been isolated from humancord blood, which suggest that they occur naturally and are present already at birth. However, theirepitope on FcεRIα was masked by IgE, and the affinity of the corresponding autoantibodies found in healthy adults appeared lowered.[10]
^Kumar, Vinay; Abbas, Abul K.; Aster, Jon (2012-05-01).Robbins Basic Pathology (9 ed.). Saunders.
^Pawankar R (February 2001). "Mast cells as orchestrators of the allergic reaction: the IgE-IgE receptor mast cell network".Current Opinion in Allergy and Clinical Immunology.1 (1):3–6.doi:10.1097/00130832-200102000-00002.PMID11964662.
^Ochiai K, Wang B, Rieger A, Kilgus O, Maurer D, Födinger D, Kinet J, Stingl G, Tomioka H (1994). "A review on Fc epsilon RI on human epidermal Langerhans cells".International Archives of Allergy and Immunology. 104. Suppl 1 (1):63–64.doi:10.1159/000236756.PMID8156009.
