IL-5 is a 115-amino acid (in human, 133 in the mouse) -long Th2 cytokine that is part of the hematopoietic family. Unlike other members of this cytokine family (namely interleukin 3 and GM-CSF), this glycoprotein in its active form is a homodimer.[5]
IL-5 has long been associated with the cause of several allergic diseases including allergic rhinitis and asthma, wherein a large increase in the number of circulating, airway tissue, and induced sputum eosinophils have been observed.[11] Given the high concordance of eosinophils and, in particular, allergic asthma pathology, it has been widely speculated that eosinophils have an important role in the pathology of this disease.[12]
Eosinophils are terminally differentiated granulocytes found in most mammals. The principal role of these cells, in a healthy host, is the elimination of antibody bound parasites through the release of cytotoxic granule proteins.[17] Given that eosinophils are the primary IL-5Rα-expressing cells, it is not surprising that this cell type responds to IL-5. In fact, IL-5 was originally discovered as an eosinophil colony-stimulating factor,[18] is a major regulator of eosinophil accumulation in tissues, and can modulate eosinophil behavior at every stage from maturation to survival. Mepolizumab is a monoclonal antibody antagonist IL-5 which can reduce excessive eosinophilia.
The IL-5 receptor is composed of an α and a βc chain.[23] The α subunit is specific for the IL-5 molecule, whereas the βc subunit also recognised by interleukin 3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF).[23][24]Glycosylation of the Asn196 residue of the Rα subunit appears to be essential for binding of IL-5.[25]
^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^"Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^Milburn MV, Hassell AM, Lambert MH, Jordan SR, Proudfoot AE, Graber P, Wells TN (May 1993). "A novel dimer configuration revealed by the crystal structure at 2.4 A resolution of human interleukin-5". Nature. 363 (6425): 172–176. Bibcode:1993Natur.363..172M. doi:10.1038/363172a0. PMID8483502. S2CID4254991.
^Bradding P, Roberts JA, Britten KM, Montefort S, Djukanovic R, Mueller R, et al. (May 1994). "Interleukin-4, -5, and -6 and tumor necrosis factor-alpha in normal and asthmatic airways: evidence for the human mast cell as a source of these cytokines". American Journal of Respiratory Cell and Molecular Biology. 10 (5): 471–480. doi:10.1165/ajrcmb.10.5.8179909. PMID8179909.
^Kaminuma O, Mori A, Kitamura N, Hashimoto T, Kitamura F, Inokuma S, Miyatake S (2005). "Role of GATA-3 in IL-5 gene transcription by CD4+ T cells of asthmatic patients". International Archives of Allergy and Immunology. 137 (Suppl 1): 55–59. doi:10.1159/000085433. PMID15947486. S2CID25517499.
^Berti A, Atzeni F, Dagna L, Del Giacco S, Emmi G, Salvarani C, Vaglio A (February 2023). "Targeting the interleukin-5 pathway in EGPA: evidence, uncertainties and opportunities". Annals of the Rheumatic Diseases. 82 (2): 164–168. doi:10.1136/ard-2022-223044. PMID36357156. S2CID253457684.
^Boggu PR, Kim Y, Jung SH (November 2019). "Discovery of benzimidazole analogs as a novel interleukin-5 inhibitors". European Journal of Medicinal Chemistry. 181: 111574. doi:10.1016/j.ejmech.2019.111574. PMID31400705. S2CID199527755.
^Giembycz MA, Lindsay MA (June 1999). "Pharmacology of the eosinophil". Pharmacological Reviews. 51 (2): 213–340. PMID10353986.
^Di Biagio E, Sánchez-Borges M, Desenne JJ, Suárez-Chacón R, Somoza R, Acquatella G (July 1996). "Eosinophilia in Hodgkin's disease: a role for interleukin 5". International Archives of Allergy and Immunology. 110 (3): 244–251. doi:10.1159/000237294. PMID8688671.
^ abTavernier J, Devos R, Cornelis S, Tuypens T, Van der Heyden J, Fiers W, Plaetinck G (September 1991). "A human high affinity interleukin-5 receptor (IL5R) is composed of an IL5-specific alpha chain and a beta chain shared with the receptor for GM-CSF". Cell. 66 (6): 1175–1184. doi:10.1016/0092-8674(91)90040-6. PMID1833065. S2CID54277241.