White Blood Cells (Leucocytes)

Erwin TaherMedical Faculty Dept of Clinical Pathology UISUOur bodies are continually eposed to !arious "icroorganis"sOur bodies ha!e a special syste" for co"bating the different infections and toic agents#This is co"posed of blood leukocytes $ tissue cells derived from theleukocytes.These cells wor% in & ways to pre!ent disease'i( by actually destroying the in!ading bacteria or !iruses by phagocytosis andii( by for"ing antibodies $ sensiti)ed ly"phocytes* one or both of which "ay destroy or inacti!ate the in!ader#+eu%ocytes' "obile units of body,s i""une syste"#I""unity is the body,s ability to resist or eli"inate potentially har"ful foreign "aterials or abnor"al cells +eu%ocytes pri"arily function as defense agents outside the blood* to carry out their function* leu%ocytes use -see% out $ attac%. strategy# /i#e# they go to sites of in!asion or tissue da"age#( +eu%ocytes are for"ed partially in the bone "arrow $ in the ly"ph tissue#The "ain reason 01Cs are present in blood is to rapidly transported fro" their sites of production or storage to where!er they are needed' areas of serious infection $ infla""ation# Thus Pro!iding rapid and potent defense# There are fi!e types of leu%ocytes* they lac% 2b so they are colourless /i#e# white( unless specifically stained for "icroscopic !isibility# Unli%e erythrocytes* / which are of unifor" structure* identical function* $ constant no#( leu%ocytes !ary in structure* function $ no#3ccording to staining properties of 01Cs* 01Cs are di!ided into LeukocytesGranulocytesPolymorphnuclearAgranulocytesUnlobed nucleusNeutrophilEosinophil Basophil LymphocyteMonocyte 4&5 #85675 9#65S"alllarge ly"phocyteTotal count' 8*777 : ;;*777 01Cs75 neutrophils 1lood pool' 65 6# Tissue pool' ?5 @enesis of 01Cs' +eu%opoiesisIn bone "arrow PHSC (Pluripotential hemopoietic stem cells) diferentiates committed stem cells CFU-GMGranulocytes & monocytes are ormed only in !one marro"# lymphocytes & plasma cells are produced in $arious lympho%enous tissues&'Cs ormed in the !one marro" are stored in the marro" & lymphocytes are stored in lymphoid tissue & small no( circulate in the !lood(Circulating poolMarginal poolAow BaC represents the "yelocytes showing neutrophilic* basophilic and eosinophilic fro" left to right# Aow BbC represents the "eta"yelocyte cells again starting with neutrophilic on the left# @ranulocytes' after released fro" bone "arrow* 8DE hours circulate in blood $ another 8D9 days in the tissues# Sur!i!e only for few hours in serious infectionMonocytes' ;7D&7 hrs in blood#Once in tissuethey swell up to "uch larger si)e to beco"e tissue "acrophage in this orm they can li$e or month(+y"phocytes' +ife span for wee% or "onths depending on body,s need#They continually circulate in blood $ "o!e fro" blood to tissues $ fro" tissues to blood and again blood to tissues#Si)e';7D;8 =" in dia"#Fucleus';# Multilobed /;D4 lobes( therefore called poly"orphnuclear leucocytes# Goung cell ha!e single horse shoe shaped nucleus# 6# 3s the cells grow older nucleus beco"es "ultilobed# +obes are connected with one another by chro"atin threads# 8# 3rneth count' More the no# of lobes* the "ore "ature is the neutrophil# More the no# of "ature cells* 3rneth count shifts to right /Hit# 1;& or folate deficiency(# More theyounger cells shit to let (inection)(Cytoplas"' contains neutrally stained granules& types of granules are present ;# Pri"ary< lysoso"al granules' less in no# Contain !arious en)y"es li%e acid hydrolase* "yeloperoidase /produces 2Cl for %illing bacteria(# These granulesare lysoso"al granules containing acid hydrolases* whichcan digestbacteria# 3fter a bacteriu" is phagocytosed by the neutrophil* pri"ary granules release their en)y"es which re"ainwithin the neutrophil $ %ill the bacteriu"* thus no har" to innocent cells# In addition* pri"ary granules also contain powerfulbroad spectru" anti"icrobial polypeptide defensin Secondary granules' "ore nu"erous# Contain i# +actoferin* ii# Hit 1;& binding protein $ iii# Co"ponents of en)y"e syste" that produce free radicals li%e 2&O&* which %ills the "icrobes#i!# Substances that facilitates che"otais#6# Toic granules' During infection toic coarse granules are seen#Functions';# Phagocytosis' 0hene!er the body gets in!aded by bacteria* neutrophils are the ;st line of defence to see% out* ingest $ %ill the bacteria# Pyrogen' They contain fe!er producing substance' endogenous pyrogen which is an i"portant "ediator of febrile response to bacteria#Hariation in count'Feutrophilia') in neutrophils( Causes are* +( Physiolo%ical,)-.ercise# /)+ter in0ection o epinephrine# 1)Pre%nancy# menstruation & lactation# 2)3e"!orn# 4)+ter meals# 5)Mental or emotional stress('( Patholo%ical ,)+cute pyo%enic (pus ormin%) inections# /)Follo"in% tissue destruction# e(%( i) 'urns ii) +ter hemorrha%e# iii) myocardial inarction# i$) +ter sur%ery$) poisonin% !y lead# mercury# insect $enomFeutropenia' in neutrophils *,) 6n children# /) 7yphoid# paratyphoid e$er# 1) 8iral inection# 2) Malaria# 4) +plasia o !one marro"# 5) 'one marro" depression(Si)e';7D;8 =" in dia"# /&5(Fucleus';# Usually /E95( cells Ibilobed,# +obes are connected with one another by chro"atin threads thus producing spectacle appearance# 6#Ae"aining ;95 cells ha!e trilobed nucleus#Cytoplas"' ;# 3cidophilic* appears light pin% in colour after staining @ranular@ranules;# Coarse* stain bright bric% red with acidic /eosin( dye# @ranules do not co!er the nucleus#6# They contain !ery high peroidase content /hista"inase(* lyso)y"es & MaJor 1asic Protein /M1P(Functions';# Mild phagocytosis' because less "otile than neutrophils Eosinophils collect at the sitesof allergic reactions $ detoifyInfla""ation inducing substances by degrading the "ediators /e#g# hista"ine* bradi%inin(6# They enter the tissues $ are specially abundant in the "ucosa of respiratory tracts* @IT* urinary tract* where they pro!ide "ucosal i""unity8# Eosinophils attac% parasites that are too large to be engulfed by phagocytosis# Eosinophil granules release che"icals /peroidase( which are toic to lar!ae of parasitesHariation in count'Eosinophilia' ) in eosinophils Causes are*- ,)+ller%ic conditions e(%( !ronchial asthma# hay e$er# 9lariasis /) Parasitic inestation# trichinosis & schistosomiasis e(%( "orms (hoo:"orm# round"orm & tape"orm)# 1) S:in disease li:e utricaria( Eosinopenia' ; in eosinophils Causes are*- ,) +C7H & steroid therapy# /) Stressul conditions# &1) +cute pyo%enic inectionsSi)e'ED;7 =" in dia"#Fucleus';#irregular bilobed* often IS,shaped $ its boundary is not clearbecause of o!ercrowding with coarse granules#Cytoplas"';# Is slightly basophilic $ appear blue* it is full of granules#@ranules';# Contain heparin* hista"ine $ 92T#Functions' ;# Mild phagocytosis Aole in allergic reaction' 1asophils release hista"ine* brady%inin* no# of lysoso"al en)y"es* slow reacting substance of anaphylais /SASD3( $ serotonin /92T(# These substancescause local !ascular $ tissue reactions that cause "any allergic "anifestations#6# +iberates heparin which i# 3cts as anticoagulant $ %eeps blood in fluid state#ii# 3cti!ates the en)y"e lipoprotein lipase' re"o!es fat particles fro" the blood after fatty "eal#Si)e' +argest 01C ;ED&7 ="#Fucleus';# Is large single unlobed* eccentric in position /present on one side of the cell(# It is notched< indented /%idneyShaped(6# It has reticulated chro"atin networ%#Cytoplas"';# Is abundant* pale blue $ usually clear with no granules#@ranules';# So"eti"es contain fine purple dust li%e granules called 3)ur granulesFunctions';# Aole in phagocytosis' These are powerful phagocytes $ capableof phagocytosing as "any as ;77 bacteria# They also ha!e ability to engulflarge particles such as A1Cs $ "alarial parasites# Precursor of tissue "acrophages'The "ature "onocyte stay in blood only for few hours $ then they lea!e blood and enter etra!ascular tissue* to beco"e tissue"acrophages#6# Aole in tu"or i""unity' %ill tu"or cells after sensiti)ation by ly"phocytes8# Synthesis of biological substances' Monocytes synthesi)e co"ple"ent $ other i"p substances li%e prostaglandin E $ clot pro"oting factors# They secrete' i) 6