CytokinesCytokinesareproteinssecretedbythecellsofinnateandadaptiveimmunitythatmediatemanyofthefunctionsofthesecells.Cytokinesareproducedinresponsetomicrobesandotherantigens,anddifferentcytokinesstimulatediverseresponsesofcellsinvolvedinimmunityandinflammation.Intheactivationphaseofadaptiveimmuneresponses,cytokinesstimulatethegrowthanddifferentiationoflymphocytes,andintheeffectorphasesofinnateandadaptiveimmunity,theyactivatedifferenteffectorcellstoeliminatemicrobesandotherantigens.Cytokinesalsostimulatethedevelopmentofhematopoieticcells.Inclinicalmedicine,cytokinesareimportantastherapeuticagentsandastargetsforspecificantagonistsinnumerousimmuneandinflammatorydiseases.Thenomenclatureofcytokinesisoftenbasedontheircellularsources.Cytokinethatareproducedbymononuclearphageocyteswerecalledmonokines,andthoseproducedbylymphocyteswerecalledlymphokines.Withthedevelopmentofanticytokineantibodiesandmolecularprobes,itbecameclearthatthesameproteinmaybesynthesizedbylymphocytes,monocytes,andavarietyoftissuecells,includingendothelialcellsandsomeepithelialcells,.Therefore,thegenerictermcytokinesisthepreferrednameforthisclassofmediators.GeneralPropertiesofCytokinesCytokinesarepolypeptidesproducedinresponsetomicrobesandotherantigensthatmediateandregulateimmuneandinflammatoryreactions.Althoughcytokinesarestructurallydiverse,theyshareseveralproperties.Cytokinesecretionisabrief,self-limitedevent.Cytokinesarenotusuallystoredaspreformedmolecules,andtheirsynthesisisinitiatedbynewgenetranscriptionasaresultofcellularactivation.Suchtranscriptionalactivationistransient,andthemessengerRNAsencodingmostcytokinesareunstable,socytokinesynthesisisalsotransient.TheproductionofsomecytokinesmayadditionallybecontrolledbyRNAprocessingandbypost-transcriptionalmechanisms,suchasproteolyticreleaseofanactiveproductfromaninactiveprecursor.Oncesynthesized,cytokinesarerapidlysecreted,resultinginaburstofreleaseasneeded.Theactionsofcytokinesareoftenpleiotropicandredundant.Pleiotropismreferstotheabilityofonecytokin...
