Antigen_ppt(_RANJITHA_SL)_.presentation.

KUVEMPU
UNIVERSITY
PG DEPARTMENT OF BIOTECHNOLOGY
SAHYADRI SCIENCE COLLEGE
SHIVAMOGA.
SEMINAR TOPIC
ANTIGENS
SUBMITTED BY
UNDER THE GUIDENCE OF
RANJITHA SL
Dr. BANUMATHI
I MSc BIOTECHNOLOGY
LECTURER
Email Id: ranjithasl810@gmail.com
PG DEPARTMENT OF BIOTECHNOLGY
SHIVAMOGGA .

CONTENT
 INTRODUCTION
 ANTIGENS
 IMPORTANCE
 TYPES
 HAPTENS
 EPITOPES AND PARATOPES
 PROPERTIES/FACTORS
 ADJUVENTS
 TESTS
 CONCULSION
 REFERENCES

INTRODUCTION
• Antigens are molecules that tigger an immune
response in the body they are recognised by the
immune system as foreign or non self .the
immune system them mounts a defense against
these antigens. Often by producing antibodies.
• Antigens can be found on the surface of
bacteria, viruses, parasites, and other foreign
invaders. They can be also be present in
substances like pollen, dust mites, and non –
self antigens, allowing it to target foreign
substances without attacking the body’s own
tissues.

ANTIGENS
• Antigens are foreign substances that can be
recognized by the immunoglobulin receptor of B
cell or by the T cell receptors when complexed
with MHC
• IMMUNOGENICITY : The ability to induce a
humor/cell mediated response is a property of
a substance known as antigen called immunogen
• ANTIGENICITY : The ability to combine
specifically with antibodies or cell surface
receptors. all molecules that have the
property of immunogenicity also have the
property of antigenicity

IMPORTANCE OF ANTIGENS
Triggering immune response
Specificity
Activation of immune cells
Antibody production
Immunological memory
Vaccine development
Cancer Research and study
Diagnostic Tools
Immunotherapy development

TYPES OF
ANTIGEN
CLASSIFICATION BASED ON ORIGIN
Exogenous Antigens
Endogenous antigens
Auto antigens
Tumors antigens

EXOGENOUS ANTIGENS
❶ ORIGIN ❷ PROCESSING ❸ IMMUNE
RESPONSE
• Exogenous antigens are
foreign substances that
originate outside the
body.
• Once exogenous antigens
enter the body ,they are
taken up by immune cells,
primarily antigen-
presenting cells(APCs).
• The presentation
of exogenous
antigen on APCs
triggers an
immune response.
• They enter the body
through various routes
such as inhalation
,ingestion or
injection.
• APCs process their antigen
and present them on their
surface in a way that is
recognizable by the other
immune cells
• This involves
the activation of
T Cells and B
Cells
• They come from sources
like bacteria ,
viruses, fungi,
parasites and allergens
• The leading to
the production of
the antibodies
and cytotoxic
then T-Lympocytes
that can target
and eliminate the

ENDOGENOUS ANTIGENS
❶ ORIGIN ❷ EXAMPLES
• These antigens are produced
within the cells of the body
• Endogenous antigens includes
viral proteins, when viruses
infect a cells they take over
the cells machinery and
produces viral proteins
• They aren't foreign invaders
like exogenous(bacteria/viruses)
instead, they are generated by
normal cellular processes, such
as protein synthesis and
degradation.
• These processes can sometimes
leads to the production of
abnormal or altered protein that
the immune system recognize as

AUTO
ANTIGENS
❶ SELF
RECOGNISATION
❷ IMMUNE
DYSREGULATION
❸ TISSUE
DAMAGE
• The immune system
normally
distinguishes
between self and
non self.
• Autoimmune disorder
occur when the immune
system loses tolerance
for self antigen
• Autoantigens can trigger
the production of
antibodies and T cells that
attack the body's own
tissues.
• Autoantigens are
molecules that are
normally found
within the body
,but are mistakenly
recognized as
foreign by the
immune system.
• This can happen due to
a variety of factor ,
including genetic
predisposition,
environment triggers ,
and infections.
• This can lead to a wide
range of symptoms depending
on the specific tissues and
organs involved
• When the immune system
attacks self antigens,

TUMOR
ANTIGENS
Tumor antigen are those antigens that are presented by the
MHC – I (Major Histocompatibility Complex) molecules on the
surface of tumor cells.
These antigens can sometimes be presented only by tumor
cells and never by the normal ones .
In this case they are called tumor specific antigens (
TASAs)and typically result from a tumor specific mutation .

ON THE BASIS OF THE IMMUNE
RESPONES
IMMUNOGENS
:These may be
protein
/polysaccharide
s and can
generate an
immune response
on their own
1
TOLEROGENS :
It induces
immune
tolerance
,meaning it
does not
trigger an
immune
response
2
HAPTENS :
These are non
– protein
,small
molecules
that requires
a carrier
molecules to
induces an
immune
response
3
SUPERANTIGEN
:Stimulate a
very strong
immune
response and
it activating
a large
number of
immune cells
4

BASED ON
FUNCTION
Classified into types:
COMPLETE ANTIGEN : Substances which can induced
antibody formation by themselves and can react
specifically with these antibodies
INCOMPLETE ANTIGEN/HAPTENS :Substances unable
to induce antibody formation on its own but can
become immunogenic when covalently linked to
protein ,called carrier protein .

HAPTENS
• Haptens is derived from the Greek
word haptein mean “to fasten”.
• The term Hapten was first coined by
karl Landsteiner.
• These are low molecular weight
substance that are antigenic but
not immunogenic
• Its biological importances
substances-drugs ,peptide hormones
, steroid hormones , can function
as hapten.
• Eg :Penicillin

DIFFERENCE
B/w ANTIGEN
AND HAPTENS

EPITOPES
AND
PARATOPES
EPITOPE(ANTIGENIC
DETERMINANT)
It includes
sugars, organic acids
and bases, amino acid
chains, hydrocarbons
and aromatic groups.
PARATOPES
The Antibodies
contains antigen
binding site

BASED ON BIOLOGICAL CLASSES OF
ANTIGEN
• T DEPENDENT ANTIGEN :Antigen that requires help
of T cells to activate B cells for antibody
production
• T INDEPENDENT ANTIGEN : Antigen directly
stimulate antibody production without the help
of T cells

PROPERTIES /FACTORS INFLUENCING OF
ANTIGENS
1. FOREIGNNESS
• Antigen must be foreignness to immune system
• According to Burnnet ’s clone selection theory , “forginness (non –
self) means substances that never contact with lymphocytes embryo
period.
2.CHEMICAL NATURE AND COMPOSITION
• Antigen are mainly proteins and polysaccharides
• Chemical nature of antigen protein ,polysaccharides ,nucleoproteins
,glycoprotein ,steroid hormones ,bacterial cells ,viruses
3.MOLECULAR SIZE
• The antigens have a molecular mass of 14000 to 600000 Da
• Highly antigenic are tetanus toxoid (50000),Egg albumin(42700
Da),Thyroglobulin (662000 Da)

CONTINUE…..
4.DEGRADABILITY
• Antigens that are easily phagocytosed are generally
more immunogenic.
• This is because for most antigen (T-dependent antigens)
the development of an immune response that the antigen
be phagocytosed , processed to helper T –cells by an
antigen presenting cell (APC).
5.DOSE AND CONCENTRATION: Higher doses and
concentration can trigger stronger immune responses.
6.GENETIC FACTORS: Genetic polymorphism and
epigenetic modification can affect immune responses to
specific antigens.

ADJUVENTS
• Substances that when mixed with an antigen and
injected with it ,enhance the immunogenicity of
that antigen.
• Used to boost the immune response when an
antigen has low immunogenicity or when small
amount of antigen are available
• Eg: The antibody response of mice to
immunization with BSA can be increased 5 fold
or more ,if the BSA is administered with an
adjuvant .
• Freund’s incomplete adjuvant : contains aqueous
solution , mineral oil , mannide monooleate.
• Freund’s complete adjuvant :Heat killed

TESTS FOR
ANTIGENS
ELISA
RIA
CFT
IMMUNOFLUORESENCE
NEUTRALIZATION TEST
IMMUNOHISTOCHEMISTRY

CONCULSION
Antigens are
substances that
stimulate an immune
response , playing a
crucial role in the
body’s defense
against pathogens and
diseases .they can
originate from inside
r outside the body ,
antigens trigger an
immune response.

REFERENCES
1.Kuby,
J.(2013),Immunology
(7th ed.).W.H.Freeman
and company
2.Gangal,Sudha and
Shubhangi Sontakke
(2020) ,Textbook of
Basic and Clinical
Immunolo.,gy . (3rd
ed )CBS Publisher

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