Post on 01-Feb-2020
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INNATEIMMUNITYNon-SpecificImmuneResponsePhysiologyUnit3
ProtectionAgainstInfection
• Thebodyhasseveraldefensestoprotectitselffromgettinganinfection• Skin• Mucusmembranes• Serousmembranes• Chemicals
• Ifapathogendoesbreachthebarriersattheentrancestothebody,thenyourimmunesystemisactivated• 2branchesofyourimmunesystem
• Innateimmunity(non-specificimmuneresponse)• Adaptiveimmunity(specificimmuneresponse)
DefensestoPreventInfectionPhysicalBarriers
• Skin• Watertightbarrier• Keptcleananddry• Sweatglandssecreteantibodies,lysozyme• Mostlyimpermeabletomicrobes
• Certainmicrobesdrillthrough(syphillis,hookworms,manyarthropodbornepathogens)
• Coughandsneezereflex• Hairsattheentranceofthenose
DefensestoPreventInfectionPhysicalBarriers
• Mucousmembranes• Non-keratinizedepithelialmembranes,oftenciliated• Linedwithmucus• Containantimicrobialchemicals• Excellentfortrappingmicrobesforexpulsion
DefensestoPreventInfectionPhysicalBarriers
• Serousmembranes• Lubricatedwithserumfrom“leakycapillaries”• Internalphysicalbarriertoinfectionofvitalorgans• Heart,lungs,andabdominalviscera• Similarprotectionbythemeningesofthebrainandspinalcord
DefensestoPreventInfectionNonspecificChemicalDefenses
• pHlevels• Gastricsecretions• Vaginalsecretions• Urine
• LowpHisdamagingtomostcells
• Lysozyme• Foundinbodysecretions:• Tears• Saliva• Sweat
• Foundingranulesofneutrophilsandmacrophages• Bindstomicrobesandperforatesthecellwall
ResponsetoInfectionImmuneSystem
• Thebodiesdefenseagainstinfectiousdisease• 2branchesofyourimmunesystem• InnateImmunity:
• Non-specificimmuneresponse• Encounterandrecognitionofantigen• Includesmultipletypesofimmunecells• Includesinflammatoryresponse
• AdaptiveImmunity:• SpecificImmuneresponse• ActivatedafterpresentationofantigenbyanAPC• Responseoflymphocytestospecificantigen
ResponsetoInfectionCellSignaling
• Immunecellssecretemorethan100differentcytokines• Cytokinesmediateeverystepoftheimmuneresponse• Allowcommunicationbetweendifferentimmunecellsandtimingofcascadereactions• Mostcytokineshavelocalactions• Paracrine/autocrineagents
• Somewillcirculateinbloodtodistanttissues• Hormones
CellsoftheInnateImmuneResponseNon-specificImmuneResponse
• Diversecollectionofcellsthatarefoundinextracellularfluid• Plasma• Lymph• Interstitium
• Non-specificImmuneResponseCells• Neutrophils,eosinophils,basophils,monocytes• Macrophage• Dendriticcells• Mastcells• NKCells• **Bcells
CellsoftheInnateImmuneResponseNon-specificImmuneResponse
• Leukocytes(WBC’s)• Neutrophils,eosinophils,basophils,monocytes• DifferentWBC’shavedifferentactions• Transportedinplasmaandmigrateintothetissueswheretheyfunction
DiapedesisandExtravasation
CellsoftheInnateImmuneResponseNon-specificImmuneResponse
• Neutrophils• Voraciousphagocytes• Opsonify pathogens
• Uselysozymesandsuperoxide(reactiveO2 species)todissolvemicrobesingested• Granulescontainanti-microbialagents
CellsoftheInnateImmuneResponseNon-specificImmuneResponse
• Neutrophils• FirstWBCataninfectionsitemediatedbychemicalmessengers• Chemotaxis• Endothelium,mastcells,macrophage
• Shortlived• 5-90hoursincirculation• 1-2daysintissue
CellsoftheInnateImmuneResponseNon-specificImmuneResponse
• Eosinophils• Slightlyphagocytic• Majorroleininfectionsinvolvingeukaryoticparasites(worms)• Alsoinvolvedin• Someallergicresponses• Dissolvingclots• Detoxifyingforeignsubstances
CellsoftheInnateImmuneResponseNon-specificImmuneResponse
• Basophils• Actionsaresimilartomastcellsoflooseconnectivetissue• Granulescontain• Heparin• Histamine
• vasodilator,increasescapillarypermeability
• Importantininflammation,especiallyrelatedtoallergies
CellsoftheInnateImmuneResponseNon-specificImmuneResponse
•Monocytes• Differentiateintomacrophageanddendriticcellsaftermigrationintolocaltissues• Storedintheredpulpofthespleen
CellsoftheInnateImmuneResponseNon-specificImmuneResponse
•Macrophage• Derivedfrommonocytes• Activatetomacrophageininterstitium• Residentpopulationsfoundinalltissues• Strategicallylocated• Epitheliaincontactwiththeoutsideofthebody• Skin,liningofdigestiveandrespiratorytract
• Linebloodandlymphvessels
CellsoftheInnateImmuneResponseNon-specificImmuneResponse
• Residentpopulationsofmacrophage• Kupfer Cells(liver)• MesangialCells(kidney)• SatelliteCells(PNS)• Microglia(CNS)• DendriticCells(skin)• DustCells(lungs)• Histocytes (c.t.)• Osteoclasts(bone)
• Macrophagearelonglived• Severalmonths
• Multipleactionsofmacrophage• Phagocytosis• Removalofcellulardebris• Tissuerepair• Woundhealing• Inflammatoryresponse
•APC
CellsoftheInnateImmuneResponseNon-specificImmuneResponse
• Dendriticcells• Locatedinepitheliumincontactwiththeexternalenvironment• Macrophagefunction
•APC
CellsoftheInnateImmuneResponseNon-specificImmuneResponse
•Mastcells• Foundinlooseconnectivetissue• Areimmatureincirculation• Migrateintotissueswheretheymature• Undergodegranulationwhenactivated• Granulescontain• Histamine• Eicosanoids• Chemokines
CellsoftheInnateImmuneResponseNon-specificImmuneResponse
CellsoftheInnateImmuneResponseNon-specificImmuneResponse
• NKCells• NaturalKillers• Lymphocytelikecell• Notimmunologicallyspecific• Performstumorsurveillance
ResponsetoInfectionInflammatoryResponse
• Inflammationaccompaniesmanyimmuneresponses• Localresponsetoinfectionorinjury• Manyimmuneprocesses
• Stimulatedbythepresenceofinfectionorallergen• Keymediatorsarephagocyticcells• Neutrophils,macrophages,dendriticcells
• Functions• Todestroyforeigninvaders• Preparefortissuerepair
• Signs:pain,heat,swelling,redness
ResponsetoInfectionInflammatoryResponse
Stepsoftheinflammatoryresponse1. Infectionorinjurycausesreleaseofchemicals2. Localvasodilation3. Increaseinproteinpermeabilityresultingindiffusionofproteinand
filtrationoffluidintointerstitialfluid4. Diapedesisandextravasationofleukocytesfromvenules into
interstitialfluidofinfected/injuredarea5. Destructionofbacteria6. Tissuerepair
ResponsetoInfectionAntigenPresentation
• Onceantigenhasbeenencounteredandrecognizedbythecellsofthenon-specificimmuneresponse• Theantigenmustbepresentedtoalymphocytetoinitiateadaptivebranchoftheimmunesystem(specificimmuneresponse)• AntigenPresentingCells(APC’s)• Macrophage• Dendriticcells• Bcells
ResponsetoInfectionDestructionofAntigen
• Oncethespecificimmuneresponsehasbeeninitiated,antibodiesareproducedfortheantigen• Antibodiesneutralizeantigen• Theantigenthatisboundbyantibodymustbedestroyed• Therearedifferentwaystodestroyantigen,dependingonwhattheantigenis• Destructionofantigenisonlyspecifictothetypeofantigen• Bacteria,virus,etc
ResponsetoInfectionDestructionofAntigen
• DestructionofBacteria• ComplimentPathway• Macrophage
• DestructionofVirus• Interferons(**)• Proteosomes• Macrophage
• ComplimentPathway(classicalpathway)• Extracellulardestructionofbacteriawithoutphagocytosis• Asuite(orfamily)ofplasmaproteins
• Sequentialactivationofcomplimentproteins• C1mustbeactivatedfirst
• Antibodiesactivatethefirstcomplementprotein(C1)• Caninvolveopsonization bytheantibody• C1bindstotheconstantarmofanantibody• Thevariablearmsoftheantibodyareboundtoabacterium
• Theendresultistheformationofaporeinthemembraneofthebacterium• Thecontentsofthebacterialcellleakout• Thebacteriumdies
ResponsetoInfectionDestructionofBacteria
Opsonization isachemicalattractant“Tomaketasty”
ResponsetoInfectionDestructionofBacteria
ResponsetoInfectionDestructionofBacteria
ResponsetoInfectionDestructionofVirus(**)
• Interferons• Interferonfamilyofcytokines• Releasedbyvirusinfectedbodycells• Actasparacrineagents• Interferonreleasedbyacellinfectedwithvirus• Interferonbindstocellsincloseproximity• Nonspecificallyinhibitsviralreplicationincellsbeforetheybecomeinfected• Protectionforhealthycellsagainstnewlyreleasedviruses• Host(tissue)specific,notvirusspecific
ResponsetoInfectionDestructionofVirus
ResponsetoInfectionDestructionofVirus
• Proteosomes• Proteincomplexes• Degradeun-needed,damaged,viralproteins
• Non-specificallydestroyproteins• Virushaveaproteincoat• Proteasescleavepeptidebonds• Proteolysis