IL-5isaninflammatorysignalingmoleculethatprimarilystimulateseosinophilproliferation,maturationandactivation.Eosinophilsareleukocytesinvolvedininflammatoryresponsesthatdefendagainstparasitesandcausesomeaspectsofasthma,allergicreactions,andperhapsautoimmunedisorders.TheactionofIL-5beginswithanimmuneresponseintissues,suchasactivationofmacrophagesandTcellsthatsecreteIL-1,IL-4andIL-6.TheimmuneresponsecanleadtoIL-5secretionbyTcells,eosinophilsandmastcells.SecretedIL-5stimulatesproductionandmaturationofeosinophilsinbonemarrowthatmigratetotissuesinresponsetoeotaxinandreleasefactorsthatdamagetissues,causingsomeoftheundesirableconsequencesofinflammation.ThereceptorforIL-5isaheterodimerofanalphasubunitthatisrequiredforIL-5selectivebindingandabetasubunitthatisalsopartoftheIL-3andGM-CSFreceptors.BindingofIL-5totheIL-5receptoratthecellsurfaceactivatesJAK/STATsignalingpathwaysthatregulatetranscription,proliferation,anddifferentiation. Contributor:GlennCroston,PhD. REFERENCES: