6Leukocytes(WhiteBloodCells)AbdullahQaswalABDALLAHSULAIMANSaleemKhraisha

00/9/2016

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Testyourself!!!

(reviewingthepreviouslectures).

Apatientcametoyourclinicwithgeneralfatigue,weaknessandshortnessofbreath.BloodtestsforthispatientshowedthatMCHC=0.3,eachredbloodcellcontains–onaverage-20*10-12gofhemoglobin,plasmavolumerepresentsabout69%oftotalbloodvolume,WBCsandplateletstogetherrepresent1%oftotalbloodvolumeandplateletsrepresent37%ofbuffycoat.(AssumethatdifferentialcountofWBCsremainedinthenormalrange).

Dependingonthiscase,answerallthefollowingquestions:

1.whichofthefollowingpossibilitiesis(are)true:

a.folicaciddeficiency.

b.leadpoisoning.

c.perniciousanemia.

d.morethanoneoftheabove.

e.extrapieceofinformationmustbeprovided.

2.hemoglobinconcentrationinthepatient’sbloodis:

a.9g/dLb.4.5g/dLc.15g/dLd.1.5g/dL

3.thepercentageofneutrophilsvolumeoftotalbloodvolumeis:

a.63%b.1%c.0.38%d.0.62%e.noneoftheabove

Answers:1.B2.A3.C

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Leukocytes(whiteBloodcells):

Generalview:

ThenormalrangeofWBCsis4000-11000cells/micro-liter(mm3)soifthenumberexceeds11000,thismeansleukocytosiswhileifthenumberislowerthan4000,thismeansleukocytopenia.

UnliketheRBCs,thereisnodifferencebetweenmalesandfemalesinthenumberofleukocytes,buteveninthesameindividualtheWBCscountchangesfromtimetotime;reachingitsmaximumintheeveninganditsminimuminthemorning.

WBCscountincreasesafterhavingameal,doingexerciseandinpregnancy.Rememberthatdoingexerciseincreasesthenumberofneutrophilsapparentlyshiftingtheequilibriumtowardsthecirculatingneutrophilsontheexpenseofthemarginatingneutrophlis(takenfromhistologylectures).

Basedontheoldclassification,WBCsaredividedinto:

1.Granulocytes:neutrophils,eosinophilsandbasophils.

2.Agranulocytes:lymphocytesandmonocytes.

RememberthatthenewclassificationofWBCsdividesthemintoGranulocytesandmononuclearleukocytesinsteadofAgranulocytesbecauselymphocytesandmonocytescontainazurophilicgranules(takenfromHistologylectures).

Granulocytescontainsinglemultilobednucleusandspecificgranules.

LifespanofWBCsdiffersdependingonthetypeofthecellrangingfrom1-4daysdaysinneutrophils,hourstoyearsinmonocytes(AccordingtoJunqueira’sbasicHistology),alsothedurationofactionisdifferentfromonecelltoanother.

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Half-lifeofWBCsdiffersdependingonthetypeofthecellrangingfromhoursinneutrophils(iftheyareintravascular)todays-monthsandsometimesaboutayearinmonocytes(AccordingtoDr.saleem).

AllWBCsareproducedfromthebonemarrowexceptforatypeoflymphocyteswhichhaveanothersiteoforiginwhichisthelymphoidtissue.IthinkthatDr.saleemwastalkingaboutBandT–memorycellssincewhenrestingBandTlymphocytesareproducedfrombonemarrowandgetimmunocompetenteitherinbonemarroworinthymusglandrespectivelytheytraveltosecondarylymphoidorgans(spleen,lymphnodesanddiffuselymphatictissue)whereanantigenrecognitionoccursproducingactivatedlymphocytes(plasmacells,T-helperandT-cytotoxiccells)andmemorycellssolymphoidorgansareconsideredasanothersourcefortheproductionoflymphocytesinadditiontobonemarrow.(takenfromhistologylectures).

Thebonemarrowisactuallyoneofthelargestorgansinthebody,approachingthesizeandweightoftheliver.Itisalsooneofthemostactive.Normally75%ofcellsinbonemarrowbelongtothewhitebloodcell-producingmyeloidseriesandonly25%arematuringredcells,eventhoughthereareover500timesasmanyredcellsinthecirculationasherearewhitecells.ThisdifferenceinthemarrowreflectsthefactthattheaveragelifespanofWBCsisshortwhereasthatofredcellsislong.

ThemeasuredcountofWBCis50%oftheactualnumberofWBCsbecausetheother50%ofWBCsareadheringtoinnerwallsofbloodvesselsandthisadheredpartiscalledMarginalpool,thesecellsarereleasedinsomeconditionssuchasinhemorrhageandhemolysis.Usuallyneutrophilshavehighercountthantheothers,

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butinrarecaseslymphocytesmighthaveacountequaltothatofneutrophilsorevenhigher.

ConcentrationsofthedifferentWBCsintheblood(Differentialleukocytecount)andthemaincharacteristicfeatureofeachthem:

1. Neutrophils:60%ofleukocytesandcharacterizedbypresenceof3-5lobesofnucleus.

2. Eosinophils:4%ofleukocytesandcharacterizedbypresenceofredtoorangegranules.

3. Basophils:lessthan1%ofleukocytesandtheirnucleusiscoveredbythelargegranules.

4. Lymphocytes:30%ofleukocytesandtheirlargenucleusoccupiesmostofthecytoplasmandifthereisasmallapparentpartofthecytoplasm,itappearsblue.

5. Monocytes:5%ofleukocytesandcharacterizedbypaleblue-greycytoplasm.

Significanceofhighwhitebloodcellscount:1.Neutrophils:increasemainlyinbacterialinfections.2.Lymphocytes:increasemainlyinviralinfections.3.Monocytes:increasemainlyinviralorfungalinfections.4.Eosinophils:increaseduringallergy,soifapatientcometoyouandyoususpectthathehasallergy,thefirsttestyouwillaskiseosinophilscount,alsoinparasiticinfections.5.Basophils:alsoincreaseinallergicreactionsbutlessthaneosinophilsdoincrease.

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Generalcharacteristicsofleukocytes:

1.Theyareabletopassthroughthewallsofthecapillariestoenterthetissues,thisprocessiscalledDiapedesis.2.Theymovebetweenthebloodvessels(fromonetoanother)inthecirculationandalsointhetissues,thisiscalledAmoeboidmotion.3.Theyareattractedtothesiteofinfectionbycertainchemicals,thisisKnownasChemotaxis.4.Theyhavetheabilitytoengulfanddigestbacteriaanddeadcells

(phagocytosis).Rememberthatmacrophages(derivedfrommonocytes)andneutrophils(microphagesorpolymorph)arecapableofphagocytosis(takenfromhistologylectures).Leukopoiesis(theproductionofWBCs):• Leukpoiesisisaverycomplicatedprocessbecauseofthe

followingpoints:1.Thestemcellisaffectedbymanyfactors(IL-1,IL-6,thenIL-3,GM-CSF,Granulocyte-CSFandstemcellfactor),ifanyoftheseisdeletedorbecomenotfunctioning,theproductionofWBCswillbeaffected.NOTE:CSFs(colonystimulatingfactors)aresocalledbecauseinvitro,ifweuseanyofthemononecellinaculture,thiscellwillproduceacolonyofcells.2.Eachoneofthesefactorsisproducedbymanycellsortissues.3.Ofcourse,therearemanystepsinleukopoiesisandineachstep,therearemanyfactorsaffecteachstepandtheproductionofthecells.

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4.Sometimesonefactoraffectsmanysteps,andthereisoverlapbetweenILsandCSF.

• Thedurationofleukopoiesisissimilartothedurationoferythropoiesiswhichisabout6days,butWBCsremaininthebonemarrowforanother6days,sotheyremaininthebonemarrowabout12days.

• DuringtheproductionofWBCs,othercells(RBCsandplatelet)

arealsoaffected,andrememberthatinperniciousanemiaevenneutrophilsareaffected,so,thereisarelationbetweentheproductionofWBCsandRBCs.

• Whenleukocytosisoccurs,ifthecauseiseliminated,thenumber

ofWBCswillreturnbacktonormal.ButifthereisagreatuncontrolledincreaseinthenumberofWBCs,thisiscalledleukemia.

Leukemia:

• ItisthemalignantproliferationofWBCsprecursorcells,orpartiallyandcompletelydifferentiatedcellsandthis

happensattheexpenseoftheproductionofRBCsandplatelets,soanemiaandthrombocytopeniaoccur.

• Causesofleukemia:1.Geneticcauses:somefamilieshavehighincidenceofleukemia.2.Environmentalfactors:theincidenceofleukemiaishighincertainareas.3.Radiation:suchaswhathappenedinNagasakiinJapan.4.Chronicexposuretosomechemicalsandsomeviruses.

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• Usually,leukemiaaffectsalltypesofWBCs,butsometimesit

doesn'taffectthe5types,soitmightbeneutrophilicleukemia,eosinophilicleukemia,basophilicleukemia,monocyticleukemiaorlymphaticleukemiaandnobodyknowswhyandhowthishappens.

• Thereare2typesofleukemia:1.Acuteleukemia:appearsmostlyinchildren,theonsetisstormy(suddenly,thepatientexperienceflu-likesymptoms:(feelingsick,havingfevers,chills,feelingfatigued),bonepain,thepatientsuffersfromanemia,tendencytobleedingandfrequentinfections).Rememberthatinacuteleukemia,themalignantcellsareimmaturegranulocyteprecursorsmainlymyeloblastsandveryfewmatureneutrophilsarebeingformedmakingthecellsineffectiveinimmuneresponseandthisexplainsthefrequentinfections(takenfromhistologylectures).2.Chronicleukemia:appearsmostlyinoldages(above45yrs),developsslowly,thesymptomsarelesssevere.

• Ingeneral,leukemiasaredividedinto2typesaccordingtotheorigin:

1-Lymphocyticleukemias2.Myelocyticleukemias

• Theleukemiacellsarebizarre(unusualinappearance)andundifferentiatedandnotidenticalwithanyofthenormalwhitebloodcells,Usuallythemoreundifferentiatedthecells,themoreacutetheleukemiais.Leukemiccellsespeciallytheveryundifferentiatedarenonfunctional,andbecauseofthat,thepatientsuffersfromfrequent

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infections.Andwithsomeofthemoredifferentiatedcells,theprocesswillbequitechronic.Effectsofleukemiaonthebody:1.Metastaticgrowthofleukemiccellsinabnormalareasofthebody.Becauseofthat,ifthediseaseisdiscoveredearly,itcanbecured,butifitisdiscoveredinlatestagestherewillbenohopeofcuring.2.Theleukemiacellsofthebonemarrowinvadethesurroundingbone,almostallleukemiaspreadtothespleen,thelymphnodes,theliverandvascularregions.3.Ineachoftheseareas,therapidlygrowingcellsinvadethesurroundingtissues,utilizingthemetabolicelementsofthesetissuesandconsequentlycausingtissuedestruction.4.Frequentinfections,severeanemiaandbleedingtendencycausedbythrombocytopenia.5.Themostimportanteffectofleukemiaonthebodyistheexcessiveuseofmetabolicsubstratesbythegrowingcancerouscells.6.Tremendousdemandsaremadeonthebodyforfoodstuffs,especiallytheaminoacidsandvitamins.Consequently,theenergyofthepatientisgreatlydepleted,rapiddeteriorationofthenormalproteintissuesofthebody.AndasEinsteinsays:”Imaginationismoreimportantthanknowledge”.

Thesheetisover