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ANTIBODYANTIBODY

GENERAL IMMUNOLOGYGENERAL IMMUNOLOGY

UNIVERSITY OF ORADEAUNIVERSITY OF ORADEA

FACULTY OF MEDECINEFACULTY OF MEDECINE

Presented by:Presented by:

Beethue Raksha DeviBeethue Raksha DeviArockiam SacchinArockiam Sacchin

Mohammad ShariqMohammad Shariq

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DEFINITIONDEFINITION

They are gamma globulin proteinsThey are gamma globulin proteinsfound in blood and used by thefound in blood and used by the

immune system to identify andimmune system to identify andneutralize foreign objects.neutralize foreign objects.

Derived from plasma cell who secreteDerived from plasma cell who secrete

hundreds to thousands of Ab perhundreds to thousands of Ab persecond per cell.second per cell.

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STRUCTURESTRUCTURE

They are typically made of basicThey are typically made of basic

structural units:structural units:

two large heavy chainstwo large heavy chains

two small light chainstwo small light chains

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LIGHT CHAINLIGHT CHAIN

There are two types of light chain:There are two types of light chain:

1.1. lambda ()lambda ()

2.2. kappa ().kappa ().

A light chain has one constant domain and oneA light chain has one constant domain and onevariable domain.variable domain.

The approximate length is 211-217 amino acids.The approximate length is 211-217 amino acids.

An AB has 2 identical light chains; either or .An AB has 2 identical light chains; either or .

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HEAVY CHAINHEAVY CHAIN

Denoted : , , , ,.Denoted : , , , ,.

The type of heavy chain present defines theThe type of heavy chain present defines the classclass ofof

antibody. Distinct heavy chains differ in size andantibody. Distinct heavy chains differ in size andcompositioncomposition

Each heavy chain has two regionsEach heavy chain has two regions

thethe constant regionconstant region The variable regionThe variable region

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CONSTANT REGIONCONSTANT REGION

Identical in all AB of the same isotype.but differsIdentical in all AB of the same isotype.but differsin antibodies of different isotypes.in antibodies of different isotypes.

For example, Ig A will have the same constantFor example, Ig A will have the same constantregion for subtypes A and B but Ig M will have aregion for subtypes A and B but Ig M will have a

different constant region.different constant region.

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VARIABLE REGIONVARIABLE REGION

differs in AB produced by different Bdiffers in AB produced by different B

cellscells

The variable region of each heavyThe variable region of each heavy

chain is approximately 110 aminochain is approximately 110 amino

acids long and is composed of aacids long and is composed of a

single Ig domain.single Ig domain.

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SPECIFIC PARTSSPECIFIC PARTS1.1. Fab regionFab region

Function: Recognise and binds the agFunction: Recognise and binds the ag

It has:It has:

1.1. variable domain (FV)variable domain (FV)

2.2. constant domainconstant domain

3.3. Complementarity Determining RegionsComplementarity Determining Regions(CDRs)(CDRs)

These are variable loops found 3 each on theThese are variable loops found 3 each on the

light (VL) and heavy (VH) chains.light (VL) and heavy (VH) chains.

2.2. Fc region (Fc region (Fragment crystallizable)Fragment crystallizable) It generates a specific immune response for aIt generates a specific immune response for a

given antigen.given antigen.

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TAXONOMYTAXONOMY

B cell differentiates and activates into fiveB cell differentiates and activates into five

antibody isotypes known as IgA, IgD,antibody isotypes known as IgA, IgD,

IgE, IgG and IgMIgE, IgG and IgM..

DDiffer in theiriffer in their ::

biological properties,biological properties, functional locationsfunctional locations,,

ability to deal with different antigensability to deal with different antigens..

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Location and FunctionsLocation and Functions

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FunctionsFunctions Antibodies are part of humoral immune system.Antibodies are part of humoral immune system.

CContributes to immunity in three waysontributes to immunity in three ways ::

1. T1. They prevent pathogenshey prevent pathogens

2.2. TThey stimulate removal of pathogenshey stimulate removal of pathogens

by macrophages and other cells by coating theby macrophages and other cells by coating thepathogenpathogen..

3. T3. Trigger destruction of pathogens by stimulatingrigger destruction of pathogens by stimulating

other immune responsesother immune responses..

Activation of complementActivation of complement Activation of effector cellsActivation of effector cells

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Activation of complementActivation of complement

BBind to surface antigensind to surface antigens,,for example, afor example, a

bacterium attract to Fc regionbacterium attract to Fc region..

KKilling of bacteriailling of bacteria isis in two waysin two ways ::

1.1. OOpsonizationpsonization

2. C2. Complement system components formomplement system components form

a membrane attack complex to assist AB to killa membrane attack complex to assist AB to killthe bacterium directlythe bacterium directly ..

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Activation of effector cellsActivation of effector cells

To combat pathogens that replicate outsideTo combat pathogens that replicate outsidecells, antibodies bind to pathogens to link themcells, antibodies bind to pathogens to link them

together, causing them to agglutinate.together, causing them to agglutinate.

Pathogen in cells that recognize their FcPathogen in cells that recognize their Fc

receptor on a particular cell triggers an effectorreceptor on a particular cell triggers an effector

function of that cellfunction of that cell

Phagocytes will phagocytosePhagocytes will phagocytose ultimatelyultimately

destruction of cell .destruction of cell .

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Medical applicationsMedical applicationsDiagnosDiagnosisis and therapy:and therapy:

1.1. EElevated IgA indicates alcoholic cirrhosislevated IgA indicates alcoholic cirrhosis..

2. E2. Elevated IgM indicates virallevated IgM indicates viral

hepatitis and primary biliary cirrhosishepatitis and primary biliary cirrhosis..

3.3. IgG is elevated in viral hepatitis,IgG is elevated in viral hepatitis,autoimmune hepatitis and cirrhosisautoimmune hepatitis and cirrhosis..

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Medical applicationsMedical applications4.4. Autoimmune disorders can often be traced byAutoimmune disorders can often be traced by

antibodies that bind the body's own epitope.antibodies that bind the body's own epitope.

5.5. Immune deficiency treatment for diseases likeImmune deficiency treatment for diseases like

1.1. X-linked agammaglobulinemiaX-linked agammaglobulinemia

2.2. HHypogammaglobulinemiaypogammaglobulinemia

Ab is used to produce passive immunityAb is used to produce passive immunity

4.4. Prenatal therapy for tPrenatal therapy for treating Rh factor .reating Rh factor .

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IImmunodiagnostic methodsmmunodiagnostic methods

ELISA,ELISA,

immunofluorescenceimmunofluorescence

Western blotWestern blot immunodiffusionimmunodiffusion

immunoelectrophoresisimmunoelectrophoresis

Magnetic immunoassayMagnetic immunoassay

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BIBLIOGRAPHYBIBLIOGRAPHY

Lippincotts biochemistryLippincotts biochemistry

http://en.wikipedia.org/http://en.wikipedia.org/