BIOLOGY 2B03 Lecture Notes - Lecture 18: Natural Killer Cell, Endothelium, White Blood Cell
Leukocytes*
These*move*out*in*response*to*local*viral*or*bacterial*infections*or*traumatic*
injury,*using*temporary*associations*
•
There*are*3*families*of*leukocytes:*
Granulocytes*
Targets*pathogens*and*includes:*neutrophils,*eosinophils*and*
basophils
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Neutrophils*are*capable*extravasation
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i.
Monocytes*
Differentiate*into*macrophages*which*engulf*bacteria*and*dead*or*
damaged*cells*
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Also*capable*of*extravasation*
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ii.
Lymphocytes*
Includes*natural*killer*cells*that*lyse*virally*infected*cells*and*tumor*
cells
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T*and*B*cells* produce*antibodies*as*part*of*the*immune*response*
and*can*undergo*extravasation*
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iii.
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Extravasation*
Capture*
The*site*of*infection*releases*cytokines*(TNF-alpha)*which*is*received*by*a*
receptor*on*the*basal*surface*of*the*endothelial*cell* *(blood*vessel*wall*
cells),*this*changes*the*behavior*of*the*endothelial*cells
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P-selectins,*which*are*held*in*regulated*secretory*vesicles,*are*
transported*the*surface*of*the*endothelial*cell*and*interacts*with*the*
ligand*on*the*surface*of*the*leukocyte
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I.
Rolling*
The*adhesion*of*the*neutrophil*to*the*endothelial*cells*slows*the*
neutrophil*movement,*the*act*of*establishing*and*losing*transient*
connections*is*called*rolling*
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II.
Slow*Rolling*
The*density*of*selectins*increases*the*closer*the*neutrophils*get*to*the*site*
of*infection
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Both*P-selectin*and*E-selectin*increase*the*association*of*the*neutrophils*
and*slows*the*movement*further
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III.
Firm*Adhesion
A*membrane*signal*on*the*endothelial*cell,*PAF,*interacts*with*a*receptor*
on*the*neutrophil*(Ex.*CXCR1*or*CXCR2)
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The*activation*of*the*PAF*receptor*causes*many*cellular*responses*in*the*
neutrophil,*which*includes*the*activation*of*integrin*
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The*activation*of*integrin*allows*it*to*interact*with*an*endothelial*ligand,*
ICAMS,*which*results*in*even*slower*movement*
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IV.
Transmigration*
The*process*by*which*the*neutrophil*has*stopped*at*the*site*of*infection*
and*is*able*to*migrate*by*crawling*between*the*endothelial*cells*
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The*connections*between*endothelial*cells*are*broken*by*enzymes*
produced*by*the*transmigrating*neutrophil
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V.
Module'8:'Lecture'2
Tuesday,* April*3,*2018
10:29*AM
Document Summary
These move out in response to local viral or bacterial infections or traumatic injury, using temporary associations. Targets pathogens and includes: neutrophils, eosinophils and basophils. Differentiate into macrophages which engulf bacteria and dead or damaged cells. Includes natural killer cells that lyse virally infected cells and tumor cells. T and b cells produce antibodies as part of the immune response and can undergo extravasation. The site of infection releases cytokines (tnf-alpha) which is received by a receptor on the basal surface of the endothelial cell (blood vessel wall cells), this changes the behavior of the endothelial cells. P-selectins, which are held in regulated secretory vesicles, are transported the surface of the endothelial cell and interacts with the ligand on the surface of the leukocyte. The adhesion of the neutrophil to the endothelial cells slows the neutrophil movement, the act of establishing and losing transient connections is called rolling.