Theinterferonsrepresentproteinswithantiviralactivitysecretedfromcellsinresponsetoavarietyofstimuli.Inmammals,classIinterferon(IFN)genesformasuperfamilyconsistingofthreegenefamilies,thealphainterferon(IFNalpha),thebetainterferon(IFNbeta)andtheinterferonomega(IFNomega)genes.TheinterferonsexhibitahugenumberofBIOLOGicaleffects.Theantiviralactivityledtothenameinterferonandservestodefinetheunitofinterferonactivity.Onpurificationofthenaturalhumanleukocyteinterferons(IFNalpha),itwasfoundthatallfractionsthatexhibitedantiviralactivityalsoexhibitedanti-growthactivity.Thisobservationwasconfirmedwithpurifiedrecombinantinterferonsandextendedtootheractivitieslike:stimulationofcytotoxicactivitiesoflymphocytesandmacrophages,naturalkillercellactivityaswellasincreaseinexpressionofsometumor-associatedantigens.Theantiproliferativeandantitumoractivitiesofinterferonhaveledtotheapplicationasanantitumoragent.Theinterferonsalsomodulatecellulardifferentiation.TheroleofIFNaasadiseaseMarkerandmarkerforimmunotherapeuticapproacheshasbeendemonstratedforanumberofdifferentindicationsandpathologicalsituations:

• DuringtheacutephaseofaviralinfectionIFNalphalevelsaresignificantlyelevatedinthemajorityofpatients.IFNalphalevelsfallsignificantlyduringtheperiodofconvalescenceatthetimeviralinfectionisindicatedbySEROconversiontests.
• IncreasedlevelsofIFNawerefoundinthemajorityofpatientssufferingfrominflammatoryarthropathieslikejuvenilepolyarthritis,rheumatoidarthritis,ancylosingspondylitis,polychondritis,psoriaticarthritis,polymyalgiarheumaticaandsclerodermia.ElevatedIFNalevelshavealsobeenshownforotherautoimmunedisorderslikesystemiclupuserythematosusandsystemicvasculitis.
• SerumIFNalphalevelscanhelptodistinguishbetweenchildrenwithnon-specificaBDominalpainormesentericadenitis,andthosewithacuteappendicitis.
• Forresistantlocalrecurrenceine.g.breastcancerandmetastaticspreadlocalinfiltrationofIFNalphaisanewinterestingapproach.IntrapleurallyadmiNISTeredinterferoncausesmeasurableserumconcentrationswhichcorrelatedwiththedegenerationofmalignantcells.