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BMT205

T Lymphocyte and MHC-ssoc ate ecogn t on

of Anti en II

11March2013

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MajorHistocompatibilityComplex

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HLA Class 1

m

Plasma membrane

3

Cytoplasm

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HLA Class 1chain has three

domains 1, 2 and 3

m

Plasma membrane

4

Cytoplasm

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MajorHistocompatibilityComplex

MHC/HLAClassI

smaller2microglobulinmolecule

and2domainsaremostpolymorphic

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HLA Class 2

The chain has two The chain has two

domains 1 and 2 domains 1 and 2

Plasma membrane

6

Cytoplasm

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MajorHistocompatibilityComplex

MHC/HLAClassII

lightchain()each

chainhastwodomains1and2

2and2domainsarenotpolymorphic

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class I

MHC

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MHCrestrictedrecogn on

of

antigen

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MHC I and MHC II Binding

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MHC I and MHC II Binding

PeptideBindingCharacteristicsofMHCI&II

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MHC I and MHC II Binding

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MHC I and MHC II Binding

Pe tideBindin CharacteristicsofMHCI&II

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Antigen Processing MHC I

Proteosome

LMP 7

Transporter

associated w/

antigen

procesing (TAP)

ABC

transporter

2 microglobulin

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Antigen Processing MHC II

CPL

compartment

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T Lymphocyte

Types of T lymphocytes / cells:

1. T Helper cell

Activate other immune system cells

. y o ox c ce

Destroy infected cells

Regulatory functions but not understood

4. Memory T cell

Provide a quick response on re-exposure

Regulate immune responses - inhibit T and B cells

activities when antigen level decline

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TCytotoxiccells

CD8glycoprotein

rec y cer a nce s

Once

activated,

induce

apoptosis

in

self

cells

n ec e w v rus; es roycancerous os ce s

Distinguishinfectedselfcells,becausethese

ce spresent

pept es

on

sur ace

n

c assImolecule

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TCytotoxiccells

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TCytotoxiccells TC cellreleasesperforin,aproteinthatforms

poresint etargetce mem rane;ce ysis

andexposepathogentocirculatingantibodies

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THelpercells

Alsocalled

CD4

Tcells

Presentanti entoThel ercellsinMHCclass

II

,

activatemacrophages,releasecytokinesthat

,

stimulateNKcells,activateBcells

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THelpercells

Playcentral

role

in

modulating

cellular

immunit viasecretionofc tokinesthatmodulate:

Bcell

activation

Immunoglobulinsecretion(quality)

Macrophageanddendriticcellactivation

Cellularchemotaxis

and

inflammation

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THelpercells

TH0 nt genpresent ng

Cytokines

H H

CarryCD4thatisMHCIIcoreceptor

ActivatedbyantigenpresentedonMHCII

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THelpercells T

H1

AssistcytotoxicTcells

xpress an acy o nerecep orname CCR5

Produces ecific

set

of

c tokines

IL

2,

TNFs,

IFN)

Involvedincellularimmunity

espons e

or

s

an

macrop age

activation

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THelpercells H

AssistB

cells

Producecytokines(IL4,5,6,10,13)

Involvedin

humoral

immunit

B

cell

activation)

Defenseagainsthelminthparasites

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THelpercells Functioninbothhumoral &cellmediatedimmunity

Stimulatedbyantigenpresentingcells(APCs)

TcellsurfaceproteinCD4enhancesactivation

Cytokinessecreted(stimulateotherlymphocytes):

- - - -

b) Interleukin4(IL4)activatesBcellsandInterleukin-2 (IL-2) cytotoxic Tcells

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THelpercells

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TC cell

CD4CD8

TCR TCR

Professional

Class II MHC

Most

nucleated

APCs:B cell

macrophagedendritic cell

cells

Target cell

Class I MHC presents processed endogenous antigen to

CD8 (cytotoxic) T cells: CD8 cells are Class I restricted

Class II MHC presents processed exogenous antigen to

27

4 e per ce s 4 ce s are ass restr cte

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ThankYou