2. CONTENTS
•INTRODUCTION
•HISTORY OF IMMUNITY
•DEFINITION OF IMMUNITY
•ANTIGEN
•ANTIBODY
•IMMUNE SYSTEM
•BARRIER DEFENSES
•CLASSIFICATION OF IMMUNITY
•INNATE IMMUNITY
•ADAPTIVE / ACTIVE IMMUNITY
•AUTO IMMUNITY
•APPLIED ASPECTS
•TREATMENT OPTIONS FOR IMMUNE DEFICIENCY
•CARIES VACCINE
•CONCLUSION
•REFERENCE
3. INTRODUCTION
• Immunity is the balanced state of having
adequate biological defenses to
fight infection, disease, or other unwanted
biological invasion, to avoid allergy
and autoimmune diseases.
4. HISTORY OF IMMUNITY
• The earliest known reference to immunity was
during the Plague of Athens in 430 BC.
• In the 18th century, Pierre-Louis made
experiments with scorpion venom and
observed that certain dogs and mice were
immune to this venom.
5. DEFINITION
• The term immunity refers to the resistance exhibited by the
host towards infection caused by micro organisms and their
products(toxins).
6. ANTIGEN:
• Any substance foreign to the body that evokes an immune response
either alone or after forming a complex with a larger molecule
(such as a protein) and that is capable of binding with a product
(such as an antibody or T cell) of the immune response.
ANTIBODY:
• Large number of proteins of high molecular weight that are
produced normally by specialized B cells after stimulation by
an antigen and act specifically against that antigen in an immune
response.
• Antibodies are also called as immunoglobulins.
8. 1. A Complete Antigen:- Substances which can
induce antibody formation by themselves and
can react specifically with these antibodies.
2. Haptens:- Substances unable to induce
antibody formation on its own but can become
can induce antibodies when linked to proteins
called carrier proteins.
CLASSIFICATION OF ANTIGEN
9. 9
Haptens
Haptens are of 2 types :
1. Complete Hapten:- can combine with specific
antibodies to form precipitates.
2. Simple Hapten:-Combine with specific antibodies
but no precipitate is produced.
10. EPITOPE
Smallest unit of antigenicity against which all
immune activity is directed
Each antibody recognizes one epitope rather
than the whole antigen
11. • Immunoglobins which are formed in the
serum and tissue fluids in response to an
antigen and react with that antigen
specifically.
ANTIBODIES/IMMUNOGLOBULINS
12. • Antibodies have 2 roles to play
(a) To bind antigen
(B) To interact with host tissues
and effector systems to remove
the antigen
13. STRUCTURE OF ANTIBODIES
• Both L and H chains
consist of 2 proteins
each having :
A variable region at
amino terminal.
A constant region at
carboxy terminal .
• Antigens combine at the
amino terminal.
15. • Major serum (Constitute 70-75% of
total immunoglobulin pool)
• IgG molecules are synthesized and
secreted by Plasma B cells.
• Normal serum concentration : 8 to
16 mg/ml (Molecular wt 150,000)
• Half life 23 days
• Transported through placenta
provides the neonate with humoral
immunity before its own immunity
developes.
IgG
16. Protects body surfaces
• Normal serum conc. 0.6 – 4.2 mg/ml (Half life
6-8 days)
• Mol wt 1,60,000
2 forms
• Structure: Dimer formed by 2 monomer units
joined together by a glycoprotein named J
chain.
IgA
SECRETORY IgA
( mol wt 160,000) .
Found on mucosal
surfaces
SERUM Ig A ( mol wt
400,000)
present in secretions
such as milk, saliva,
tears etc
17. Protects blood stream
• 5 -8 % of serum Igs
• Serum conc. 0.5 – 2 mg/ml
• Half life 5 days
• Present on the surface of immature B
cells.
• Earliest Ig formed by foetus
• Structure: pentamer ( J chain joining
the basic 5 monomer units)
• Appears early in response to infection
before IgG. Hence its presence in
serum indicates recent infection.
• Cannot cross placenta
IgM
18. • Serum conc. 3mg per 100 ml
• Mostly intravascularly present
• Mol wt 1,80,000
• Half life 3 days
• Present on the surface of B cells
• Structure similar to Ig G
IgD
19. Mediates Reaginic
Hypersensitivity
• Only Ig which is heat labile
• Serum contains only traces
• Mostly distributed extravascularly
• Mol wt 190,000
• Half life 2-3 days
• Structure resembles Ig G
• Mainly produced in the linings of
respiratory and intestinal tracts
• Mediates type 1 anaphylactic
hypersensitivity reaction via
mast cells sensitization
• Cannot cross placental barrier
IgE
20.
21. ANTIGEN ANTIBODY REACTIONS
Antigen combines with its specific antibody in an observable manner
Uses
In the Body (In vivo)
Forms the basis of immunity against infectious diseases.
In the laboratory ( in vitro) Serological reactions:
For diagnosis of infections
Detects the quantity of antigens or antibodies.
i)Precipitation reaction
ii)Agglutination reaction
iii)ELISA
22. Serological reactions
Precipitation Reaction.
• When a soluble antigen combines with its antibody in
the presence of electrolytes at a suitable temperature &
pH, the antigen – antibody form an insoluble precipitate,
this is called precipitation reaction.
• When, instead of sedimenting, the precipitate remains
suspended as floccules its known as flocculation
reaction.
Application:
– Slide test –VDRL test for syphilis.
– Tube test– Kahn test for syphilis is tube
flocculation.
– Immunodiffusion(Precipitation in Gel) –
Elek’s test for toxicity in Diptheria Bacilli.
23. IMMUNE SYSTEM
• It is a system of biological structures and processes within an
organism that protects against disease.
• Immune system detects a wide variety of agents, from viruses to
parasitic worms.
• The immune system recognizes foreign bodies and resulting in
production of immune cells and proteins.
• Barriers prevent the entry of disease causing micro organisms into
the body thus acts as protective barrier to the body.
24. BARRIER DEFENSES
• The barriers prevent the entry of pathogens to
resist infection.
• The various non specific defense mechanisms are
present.
1. Anatomical and physical barriers
2. Physiological and chemical barriers
3. Biological barriers
4. General barriers
25. Anatomical and Physical barriers
• These include
Ex; Skin
Mucous membrane,
Coughing and sneezing, etc.
26. Mucous membrane
-The respiratory , GIT etc. lined by
mucous membrane
-It blocks the micro organisms
because of its sticky nature.
Coughing and Sneezing
-The mechanical actions may help in
driving out the foreign particles that
enter the digestive and respiratory
tracts.
27. Physiological and chemical barriers
• Human milk:
This is very rich in anti bacterial substances.
Ex:IgA, lacto ferritin etc. they fight against E.coli and
Staphylococci.
• Secretions from the digestive tract:
-Stomach has microbicidal effect.
-This is due to the presence of Hcl in the gastric juice.
- This Hcl is secreted by oxyntic cell lining stomach.
• Nasal secretion and saliva
• Interferons
• Complement System
28. Biological barriers
• These includes mono nuclear phagocytic system which was
originally called reticulo-endothelial system(RES).
• Biological barriers include endocytosis.
• Endocytosis: it is the process in which cells absorb materials from
the out side of the environment by engulfing them with their cell
membrane.
Types: the absorbing of material from the out side of the
environment of cell is commanly divided in to 2 types.
1.Phagocytosis.
2.Pinocytosis
29. General barriers
• Age :
- The very young and very old are most susceptable to infections.
Ex: 1. Fetus is protected by placental barriers.
2. At old stage people have reduce or loss the host defences.
• Racial immunity, Ex- In some parts of Africa resistance to
Plasmodium falciparum malaria is seen.
• Individual immunity, Ex- Several factors such as age, hormones and
nutrition influence the level of innate immunity in an individual
30. Structure and Function of Immune
System
• Lymphoreticular cells consist of lymphoid & reticuloendothelial cells
Lymphoid cells Reticulo-endothelial Cells
Lymphocytes Plasma cells PMN cells Macrophages
(concerned with specific immune response) (concerned with the non-specific immunity)
The immune response to an antigen can be of 2 types:
I ). Humoral or Antibody mediated immunity
II ). Cellular mediated immunity.
• Humoral immunity is mediated by antibodies produced by plasma cells &
present in blood & body fluids.
• Cell mediated immunity by sensitized lymphocytes.
31. • Lymphoid organ is classified into central and peripheral
lymphoid organs.
Central lymphoid organs:
Produces mature cells of the
immune system.
– Bone marrow.
– Thymus.
Peripheral lymphoid organs:
-Major sites of interaction of mature circulating
lymphocytes with antigen, and with each other.
-Contain lots of B and T cells as well as accessory cells.
– Lymph nodes.
– Tonsils and adenoids.
– Spleen.
– MALT or GALT (Mucosal OR Gut-Associated Lymphoid
Tissue)
32. Central lymphoid organ
• Central (primary) lymphoid
organs are the sites for
generation and early
maturation of lymphocytes
(B and T cells)
• T cells mature in the thymus
• B cells mature in the bone
marrow
33. Peripheral lymphoid organs
• Traps antigens.
• These are the
sites for initiation
of most immune
response.
• Provide signals for
recirculation of
lymphocytes.
35. INNATE IMMUNITY
• It Is the natural resistances with which a person is born.
• Microbes first encounter the epithelial layers, physical
barriers that line skin and mucous membranes.
• Due to this, inflammatory response stimulates general
defenses
-Stimulates chemical signals (CYTOKINES)
-Antimicrobial Substances,
-Fever,
-Phagocytic activity
• Through these approaches, innate immunity can
prevent the colonization, entry and spread of microbes.
36. ANTIMICROBIAL PEPTIDES AND PROTEINS
• Peptides and proteins function in innate defense by
attacking microbes directly or preventing their
reproduction.
• Interferon activates macrophages to fight against
viruses.
38. Inflammatory Responses
• Following an injury, mast cells release histamine,
which promotes changes in blood vessels; this is
part of the inflammatory response.
• These changes increase local blood supply and
allow more phagocytes and antimicrobial proteins
to enter tissues leads to the formation of PUS.
• Pus, a fluid rich in white blood cells, dead microbes,
and cell debris, accumulates at the site of
inflammation.
39. Complement System
• System of some non-specific proteins present in
normal human serum,which are activated
characteristically by antigen-antibody reaction.
40. Complement
activation
• Activation occur either
by
i) Classic pathway
through antigen-
antibody complexes
ii) Alternate pathway via
non-immunologic
agents such as
bacterial toxins,
cobra venoms .
41. Humoral Response
• By antibodies circulating in blood
• Characteristic pattern of antibody production:
• Lag phase: immediate stage following antigenic stimulus
during which no antibody is detectable in circulation
• Log phase: steady rise in titre of antibodies
• Plateau: equilibrium between antibody synthesis and
catabolism
• Decline phase: catabolism exceeds production, titre falls
42. Cell Mediated Immune Response (CMI)
• Specific response which do not involve antibodies
• Mediated by sensitised T cells.
• CMI play important role in :
-Delayed hypersensitivity,
-Immunity against infectious diseases caused by
viruses,
-Graft versus host response
-Immunity against cancer
-Pathogenesis of autoimmune diseases
43. Active immunity
• It is the production of immunity against particular organisms after
exposure.
Natural active immunity:
This immunity develops by natural processes like infections.
Ex:the infection like small pox are cured by the active function of
the immune system.
Artificial active immunity:
- Here instead of natural infections.
- Infection is created artificially by using various types of vaccines.
Ex: polio vaccine, cholera vaccine etc.
44. Key Points
-Active immunity takes several
weeks to become active but passive
is immediate.
-Memory cells are only produced in
active immunity.
Natural active immunity is
Sub divided into:
Naturally acquired active immunity:
- Occurs when a person is exposed to a live
pathogen and developing a primary immune
response, which leads to immunological
memory.
- This type of immunity is “natural” because it
is not induced by deliberate exposure.
Naturally acquired passive immunity: -
- Maternal passive immunity is a variant of it.
-It refers to antibody-mediated immunity conveyed to a fetus by
its mother during pregnancy through placenta.
- IgG is the only antibody that can pass through the placenta.
45. MECHANISM OF ACTION OF VACCINE
VACCINE
PRIMARY RESPONSE
B &T LYMPHOCYTE STIMULATION
MEMORY CELLS
SECONDARY RESPONSE AS A RESULT OF
EXPOSURE TO ANTIGEN
46. ARTIFICIAL ACQUIRED IMMUNITY
Artificially acquired active immunity:
- It can be induced by a vaccine, a substance that contains antigen.
- A vaccine stimulates a primary response against the antigen without
causing symptoms of the disease.
Artificially acquired passive immunity:
- It is a short-term immunization induced by the transfer of antibodies,
which can be administered in several forms;
a) as human or animal blood plasma, as pooled human
immunoglobulin for intravenous (IVIg) or intramuscular (IG) use, and
in the form of monoclonal antibodies (MAb).
***Immunity derived from passive immunization lasts for
only a short period of time, and there is also a potential
risk for hypersensitivity reactions.
47. Auto Immunity
• A condition in which structural & functional damage is produced by
the action of antibodies against the normal constituents of the body
Conditions of Auto Immunity:
• An elevated level of immunoglobulins or demonstrable antibodies.
• Deposition of immunoglobulins or their derivatives &lymphocytes
& plasma cells at the site of lesion.
Genetic predisposition & female predominance.
Benefit from corticosteroid or immunosuppressive drugs.
48. Aetiology for auto immunity:
• Normal Cells or tissue may undergo antigenic variation
by physical, chemical & biological influences,
Such altered or neo antigens may elicit an immune response.
• Physical agents or irradiation
• Several drugs & chemicals.
• Infectious agents particularly viruses and bacterial enzymes.
50. Treatment
• Glucocorticoids.
• Anti cancer drugs like nitrogen mustards,nitros ureas.
(cyclophosphamide being the most potent)
• Antimetabolites
–Folic acid analogues such as methotrexate
–Purine analogues like azathioprine
–Pyrimidine analogues like fluorouracil
52. DIAGNOSIS OF DISEASE-
Antigen antibody reactions- used for the purpose
of diagnosis of many diseases
a) VDRL - syphilis - precipitation test
b) WIDAL - typhoid
- agglutination test
c) ELISA - HIV,TB
53. THERAPEUTIC RESPONSE
• To check for increasing or decreasing
Ag-Ab titre
• Test repeated in a week or 10 days
• Example- VDRL (syphilis)
Widal (typhoid)
54. PREVENTION &
TREATMENT OF DISEASES-
• Active and Passive immunization against
many diseases by vaccines &
immunoglobulins.
58. Immune Deficiency Diseases
• Occur due to lack of some components or some defective
components of immune system.
• Opportunistic organisms which takes advantage of
defective immune system.
• Two types
– Congenital- Inherited and occur due to defects in
B cell, or T cell or both
– Acquired- Occur due to infection of some organisms
59. Immunodeficiency Disorder Involving
T-cells
• Di- george syndrome- heart defects, poor immune system
function, a cleft palate, behavioural and emotional problems.
• Chronic mucocutaneous candidiasis- chronic infections
with Candida that are limited to mucosal surfaces, skin and
nails.
• Acquired T-cell Immunodeficiency syndrome-
lymphocytopenia of T cells or by decreased function of
individual T cells.
60. - It is caused by infection with HIV.
• HIV disrupts the immune process by directly infecting the
helper T-cells.
• Once the infected helper T-cells are activated, they work
to create new viruses .
• In addition, many helper T-cells are destroyed in the HIV
replication process.
Acquired Immune Deficiency Syndrome (AIDS)
61. Laboratory tests to diagnose an immune disorder include:
Blood tests.
-HIV test.
-Immunoglobulin levels in the blood.
-T (thymus derived) lymphocyte count.
-White blood cell count.
Prenatal testing
-Samples of the amniotic fluid, blood or cells from the tissue that
will become the placenta (chorion) are tested for abnormalities.
Genetical Disorders
In some cases, DNA testing is done to test for a genetic defect.
Test results make it possible to prepare for treatment soon.
63. • Any type of major surgery can stress the body
and suppress the immune system.
• It can take a couple of weeks to many months for
the immune system to recover fully.
• During this time, patients are more prone to
infections that can affect any area of the body,
such as the sinuses, throat, mouth, lungs, skin,
and urinary tract.
64. Factors that relates with the increased risk of
infection, are:
• The extent of surgery (number and size of incisions)
• Any complications during surgery, such as excessive bleeding
• Other medical problems, such as diabetes or heart or lung
problems
• Previous cancer treatments, such as chemotherapy or
radiation
66. Immunoglobulin therapy
It consists of antibody proteins needed to fight infections.
-It can either be injected IV or IM
-IV treatment is needed every few weeks.
-IM is needed once or twice a week.
67. • Gamma interferon therapy-
- Interferons are naturally occuring
substances that fight viruses and stimulate
immune system cells.
• Growth factors-
-When immune deficiency is caused by a
deficiency of white blood cells, growth factor
therapy stimulates the levels of white blood
cells.
69. PRINCIPLE
• Production of enzyme inhibiting antibodies
• Prevention of bacterial accumulation on teeth
Best time – age of one
(after teeth have emerged but before colonization of
streptococcus mutans)
70. TOPICAL APPLICATION HAS BEEN SUGGESTED:
Mouthrinse or Painting tooth with antibodies.
IF ANTIBODIES ARE TO BE EFFECTIVE, THEY HAVE TO
HOST GENERATED TO ENSURE A CONTINUOUS
SUPPLY.
ROUTE OF ADMINISTRATION
71. • ORAL VACCINE HAS BEEN SUGGESTED TO BE SAFER
THAN AN INJECTED VACCINE.
ENCAPSULATED PILL WHOSE CONTENT IS NOT
RELEASED UNTIL IT REACHES PEYER’S PATCHES.
75. CONCLUSION
• It is the immune system that determines the
level of resistance an individual possess to an
external stimuli.
• The immune system is like a double edged
sword. It renders an individual ineffective to any
disease or infection, on the other hand a
compromised or exaggerated immune response
would lead to fatal results.
76. REFERENCES
• Textbook Of Medical Physiology-Guyton And
Hall
• Textbook Of Microbiology By C.P. Baveja
• Textbook Of Pathology By Harsh Mohan
• Textbook Of Physiology By Prof A.K. Jain
Editor's Notes
The antigens may combine with an antibody to form antigen antibody complex
Lance-grouping beta hemolytic bacteria based on the carbohydrate composition of bacterial antigens found on their cell walls
loosely organized lymphoid follicles known as the mucosa-associated lymphoid tissue (MALT)
Cmc-also associated with HPV]
22q11.2 deletion syndrome
