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8/14/2019 General Immunology University of Oradea Faculty Of
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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/