2. Introduction
Innate Immunity
Acquired Immunity
Antigen
Antibody
Antigen-Antibody reaction
Structure and function of the immune system
Immune Response
Complement System
2
3. 3
IMMUNOLOGY-
Is the study of host defence
mechanism
IMMUNITY-
Refers to the resistance
exhibited by the host towards
injury caused by
microorganisms and their
products
6. Phagocytic cells reach the sites of inflammation in
large number,attracted by chemotactic
substances,and ingest particulate material.
Bacteria are phagocytosed into a vacuole,which
fuses with lysosomes found in the cells to form the
phagolysomes.
The phagocytosis in protection against infection is
evidenced by enhanced susceptibility to infection
seen either when the phagocytic cells are depleted
as in agranulocytosis.
7.
8.
9. COMBINED IMMUNISATION – ACTIVE PLUS
PASSIVE
ADOPTIVE IMMUNITY – INJECTION OF
IMMUNOLOGICALLY COMPETANT
LYMPHOCYTES (TRANSFER FACTOR)
10. Types of Vaccine:
Immunizing agents that are used for immunoprophylaxis
Bacterial vaccines:
◦ Live (BCG vaccine for T.B.).
◦ Killed (Cholera vaccine).
◦ Subunit (Typhoid Vi antigen).
◦ Bacterial products (Tetanus Toxoid).
Viral Vaccine:
◦ Live (Oral polio vaccine – Sabin).
◦ Killed (Injectable polio vaccine – Salk).
◦ Subunit (Hepatitis B-vaccine).
Combinations
If more than one kind of immunizing agent is included in the vaccine, it
is called a mixed or combined vaccine.
DPT (Diphtheria – pertussis - tetanus)
MMR (Measles, mumps and rubella).
DPTP (DPT plus inactivated polio).
11. Antibodies may demonstrated by variety of
techniques:
Agglutination
Precipitation
Complement fixation
Hemagglutination inhibition
Neutralisation
ELISA
12. 12
LOCAL
IMMUNTIY
(Besredka
1919-24)
Treatment of
infections that
are localized or
where it is
operative in
combating
infection at the
site of primary
entry of the
pathogen
HERD IMMUNITY
Overall level of
immunity in a
community and
is relevant in the
control of
epidemic disease
13. An antigen has been defined as any substance which when
introduced parenterally into the body stimulates the production of an
antibody with which it reacts specifically and in an observable
manner.
The two attributes of antigenicity are:
Induction of an immune response (immunogenicity).
Specific reaction with antibody or sensitized cells (immunological
reactivity).
Based on the ability of antigens to carry out these two functions, they
may be classified into different types:
Complete antigen is able to induce antibody formation and produce a
specific and observable reaction with the antibody so produced.
Haptens are substances, which are incapable of inducing antibody
formation by themselves, but can react specifically with antibody.
14. Size: Large molecular size (6.75 million) : highly antigenic
Low molecular size (<5000) : less or non-antigenic
Chemical nature: Proteins and polysaccharides : highly antigenic.
Lipids and nucleic acids : less antigenic.
Susceptibility to tissue enzymes: only substances, which are
metabolized and are susceptible to the action of tissue enzymes,
behave as antigens.
Foreignness: Only antigens that are foreign to the individual (non
self) induce an immune response.
Antigen Specificity:
It is the position of the antigenic determinant group in the antigenic
molecule at ortho, meta and para positions which determines
antigen specificity. It is not absolute. Cross reaction can occur
between antigen which bear stereo-chemical similarities.
15. Iso specificity: Isoantigens are antigens found in some but
not all member of a species. A species may be grouped
depending on the presence of different antigens in its
members; e.g. human erythrocyte antigen based on which
individuals can be classified into different blood groups.
Autospecificity: Autologous or self-antigens are ordinarily
non-antigenic but there are exceptions.
Organ specificity: some organs, such as brain,kidney and
protein of different species ,share same antigen.such
antigens, characteristic of an organ or tissue and found in
different species called as organ specific antigens.
16. Depending on the ability to produce antibody
formation, antigen are classified as
o T cell dependent (TD): structurally more complex
o T cell independent (TI): simple, limited number of
repeating epitopes
Although antibody is produced by B-
lymphocytes, but it requires cooperation of T-
lymphocytes
16
17. Following the introduction of an antigen into
an animal, certain substances called
ANTIBODY appeared in the serum and tissue
fluid,and reacted with the antigen specifically
and in some observable manner.
18.
19.
20. Antigens and antibodies, by definition, combine with each
other specifically and in an observable manner.
In vivo, they form the basis of antibody mediated
immunity in infectious diseases, or of tissue injury in some
types of hypersensitivity and autoimmune diseases.
In vitro ,In the laboratory, they help in the diagnosis of
infections,in epidemiological surveys, in the identification
of infectious agents and of noninfectious antigens such as
enzymes.
In general, these reactions can be used for the detection
and quantitation of either antigens or antibodies.
Antigen-antibody reactions in vitro are known as
serological reactions.
21. 1. The reaction is specific, an antigen combining
only with its homologous antibody and vice
versa.
2. Entire molecules react and not fragments.
3. There is no denaturation of the antigen or the
antibody during the reaction.
4. The combination occurs at the surface. Therefore,
it is the surface antigens that are immunologically
relevant.
22. 5. The combination is firm but reversible. The firmness of
the union is influenced by the affinity and avidity of the
reaction.
Affinity refers to the intensity of attraction between the
antigen and antibody molecules.
Avidity is the strength of the bond after the formation of
the antigen-antibody complexes.
6. Both antigens and antibodies participate in the
formation of agglutinates or precipitates.
7. Antigens and antibodies can combine in varying
proportions, unlike chemicals with fixed valencies. Both
antigens and antibodies are multivalent.
23. Two important parameters of serological tests
are:
1. Sensitivity: refers to the ability of test to
detect even very minute quantities of antigen
or antibody.
-when a test is highly sensitive, false
negative results will be absent or minimal.
2. Specificity: refers to ability of test to detect
reactions between homologous antigens and
antibodies only,and with no other.
-in a highly specific test,false positive
reaction are absent or minimal.
24. 24
PRECIPITATION
REACTION
• Ring test
• Slide test
• Tube test
• Immunodiffusion
• Electroimmunodiffu
sion
AGGLUTINATION
REACTION
•Slide agglutination
•Tube agglutination
•The antiglobulin
(Coombs) test
•Passive agglutination
test
Complement
Fixation Test
• Indirect
compliment
fixation test
• Conglutinating
complement
absorption test
• Other
complement
dependent
serological tests
NEUTRALIZATION
TESTS
• Viral Neutralization
Test
• Toxin
Neutralization
OPSONIZATION
IMMUNOFLUORESCENCE
RADIOIMMUNOASSAY
ENZYME IMMUNOASSAYS
• Enzyme Linked
Immunosorbent Assays
CHEMILUMINESCENCE
IMMUNOASSAY
IMMUNOELECTROBLOT
TECHNIQUES
IMMUNOCHROMATOGRAP
HIC TESTS
IMMUNOELECTRONMICROSCOPIC
TESTS
• Immunoelectronmicroscopy
• Immunoferritin Test
• Immunoenzyme Test
25. The lymphoreticular system is a complex
organisation of cells of diverse morphology
distributed widely in different organ and
tissues of the body responsible for immunity.
Lymphoreticulae cells consist of lymphoid
and reticuloendothelial components,with
clearly demarcated function.
The immune response to an antigen,whatever
its nature,can be of two types:
1. Humoral or antibody mediated immunity
2. Cellular or cell mediated immunity
28. T CELLS B CELLS
Bind to sheep erythrocytes
forming rosettes by the CD2
ANTIGEN
Bind to sheep erythrocytes coated
with the ANTIBODY and
COMPLEMENT, forming the EAC
rosettes
Have T cell receptors on their
surface composed of two
polypeptide chains, linked by CD3
Have immunoglobulin on their
surface
Have thymus-specific antigens Absent
Undergo blast transformation on
treatment with mitogens
Similar tranformation with
bacterial endotoxins
Under microscope – generally free
of cytoplasmic surface projection
Have an extremely filamentous
surface with numerous microvilli
28
The most clear cut
differentiation between T and B
cells is by their surface markers
29. STEM
CELLS
CYTOPL
ASMIC 3
Surface CD
markers 7 Pro-
T
thymus 7,-2 Pre-T
7,2,3
1,4,8
TCRαβ
Extra
thymic
7,2,3,4
TCR
Helper/inducer
7,2,3,8
TCR
Cytotoxic/supressor
7,2,3
TCRγδ
Immature
-T
Mature-
T
Bone marrow
30. B lymphocyte precursors,pro B cells,develop in the
fetal liver during embyonic life,and in bone marrow
afterwords during throughout life.
Rearrangement of immunoglobulin genes takes
place on their becoming pre-Bcells,which synthesis
cytoplasmic IgM.
In the next stage immature Bcells-IgM expressed
on the cell surface.
These cells migrate to periphery and undergo
immunoglobulin isotype switching so that instead
of IgM alone,the cell express on its surface IgD,as
well as one of other Ig classes.
31. By reassortment of Ig genes,B cells develop the
capacity to produce Ig molecule which can react
with all possible epitopes.
By a process of allelic exclusion,each B cells
becomes programmed to form only one class of
Ig,with either kappa or lambda light
chain,possessing specificity to a single epitope
alone,and to exress it on the cell surface.
On contact with its appropriate antigen,the mature
B cells undergone clonal proliferation.
Some activated B cells become long lived memory
cells responsible for the recall phenomenon seen
on subsequent contact with same antigen.
32.
33. Discovered by Gorer in 1930s.
Gorer identified two blood group antigen system in mice.
-antigen 1 was common to all the strains.
-antigen 2 was found only in some strain and appeared to be
responsible for allograft rejection,this was called as H-2
antigen.
H-2 antigen system was found to be the major
histocompatibility antigen for mice and to be coded for by a
closely linked multiallelic cluster of genes,which was called
the major histocompatibility complex.
Dausset done study on human leucocyte antigens,which were
later found to be the major histocompatibility antigen in
human beings.
34. MHC genes found on a segment of one
chromosome pair,coding for three different
classes of proteins:
1. Class1protein: that determine
histocompatibility,and acceptance or rejection of
allograft.
2. Class2 protein:that regulate immune response.
3. class3 proteins: that include some components
of the complement system.
35. Human Leukocyte Antigens Complex:
-the HLA complex of genes is located on short arm
of chromosome 6.
-it consist of three separate cluster of genes:
1. HLA class1 comprising A,B and C loci;
2. Class2 or D region consisting of DR,DQ and DP
loci;
3. Class3 or the complement region containing
genes for complement components C2 and C4
of the classical pathways,as well as properdin
factor B of alternative pathway,heat shock
proteins.
36. HLA molecules:
-HLA antigens are two chain glycoprotein molecules
anchored on the surface membrane of cells.
1. Class1 molecules:consist of heavy peptide chain
noncovalently linked to a much smaller peptide
called beta 2-microglobulin.
-The beta chain has constant aminoacid sequence
and is coded for by a gene on chromosome 15.
-The alpha chain consist of three globoid domains
which protrude from the cell membrane and a
small length of transmembrane C terminus
reaching into cytoplasm.
-HLA class1 antigen are found on the surface of all
nucleated cells.
37. HLA class2 antigens:are heterodimers,consisting
of an alpha and beta chain.
-Each chain has two domain,the proximal domain
being the constant region and distal the variable.
- HLA class2 antigens are more restricted in
distribution,being found only on cells of immune
system:macrophages,dendritic cells,activated T
cells and particularly on B cells.
38.
39. 39
The importance of MHC antigens in
immune reaction is indicated by finding
that T cells respond to processed
antigens on the macrophages and other
accessory cells only when they are
presented along with the self – MHC
antigen
40. 40
ANTIBODY MEDIATED
IMMUNITY (AMI)
When body develops
antibodies capable of
attacking the invading
agent
CELL MEDIATED
IMMUNTIY (CMI)
Immunity achieved
through formation of
large number of
activated T
lymphocytes that are
specially crafted in the
lymph nodes to
destroy the foreign
agents
The specific reactivity induced in
a host by an antigenic stimulus is
known as host response
41. Humoral immune response:
- The production of antibodies consists of three steps:
The entry of the antigen, its distribution and fate in
the tissues and its contact with appropriate
immunocompetent cells (afferent limb).
The processing of antigens by cells and the control of
the antibody forming process (central functions).
The secretion of antibody, its distribution in tissues
and body fluids and the manifestations of its effects
(efferent limb).
42. Antibody production follows characteristic pattern:
1. Latent period or lag phase
2. Rise in titre of serum antibody
3. Steady state of antibody titre
4. Decline of antibody titre
43. CMI refers to the specific immune response that does not involve
antibodies. They include delayed hypersensitivity (DH), which
results in injury rather than protection.
- CMI participates in the following immunological functions:
1. Delayed hypersensitivity.
2. in infectious diseases caused by obligate and facultative
intracellular parasites.
- bacteria (for example, tuberculosis, leprosy)
- fungi (for ex. Histoplasmoses)
- protozoa (ex. Leishmaniasis) and
- viruses (for ex: measles, mumps)
3.Transplantation immunity and graft versus host reactions.
4.Immunological surveillance and immunity against cancer.
5.Pathogenesis of certain autoimmune diseases (thyroiditis).
44. Cytokines:
-cytokines are peptide mediaters or
intercellular messengers that regulates
immunological,inflammatory and reparative
host responses.
-they are highly potent hormone like
substances,active even at low concentrations.
45. CLASSIFICATION OF CYTOKINES:
1.Interleukins:
IL1-proliferation and differentiation of T,B and other cells
IL2-promot growth and differentiation of T and B cells
IL3-multi-CSF
IL4-proliferation of B and cytotoxic T cells,increase IgE production
IL5-stimulates IgA,IgM production
IL6-promote B cells differentiation,IgG production
2.Colony stimulating factor-T cell and macrophage growth stimulation
3.Tumour necrosis factor-tumour cytotoxicity,lipolysis,induce cytokine
4.Interferons:antiviral activity,MHC class1&2 expression on cell
5.Other cytokines:
-Transforming growth factor beta-inhibit T and B cell proliferation
-leukemia inhibitory factor-proliferation of stem cells
46. THEORIES OF IMMUNE RESPONSE:
Theories of immunity fall into two categories,
instructive and selective.
Instructive theories postulate that an
immunocompetent cell is capable of synthesizing
antibodies of any specificity. The antigen encounters
an immunocompetent cell and instructs it to produce
the complementary antibody.
Selective theories, on the contrary, shift the emphasis
from the antigen to the immunocompetent cell.
They postulate that immunocompetent cells have only
a restricted immunological range. The antigen exerts
only a selective influence by stimulating the
appropriate immunocompetent cell to synthesize an
antibody.
48. Refers to a system of factors that occurs in
normal serum and are activated
characteristically by antigen-antibody
interaction and subsequently mediate a
number of biologically significant
consequences.
The complement system belongs to the
group of biological effector mechanisms
called triggered enzyme cascades which also
includes coagulation, fibrinolytic and kinin
systems.
49. Complement system is activated by two
pathways.
1. Classical pathway.
2. Alternative pathway.
50. 5
0
CLASSICAL C PATHWAY ALTERNATIVE PATHWAY
E
A
C
1
EA
C1 C1
Esterase
C
4
C
4a
C
4b
EAC1
4b Mg
++
C
2
C
2a
C
2b
C14b2a/
C3
converta
se
C
3
C
3a
C
3b
C3b in
circulation ACTIVATOR,
i.e. endotoxin
C3b
(Bound)
Inactivated by serum
protein factors H & I
Serum
protein
Factor B/
C3
proactivato
r
Mg
++
C3
bB
C3bBb/
C3
convertase
Serum protein Factor
D/ C3 proactivator
convertase
Ba Bb
C
3
C
3a
C
3b
Stabilise
d by
Factor P
CASCADE
51. 51
Title Journal
and year
methodolog
y
Author’s
conclusion
Remarks Level of
evidence
The Role
of
Immunolo
gy in
Periodont
al Disease
RUSSELL J.
NISENGAR
D
Journal of
periodont
ology
1977
Observation
al study
Neutrophil
dysfunction likely
contributes to the
pathogenesis of
periodontitis.
This dysfunction
disrupts the
protective host
response to the
bacteria.
Development of
periodontitis
probably requires
both the
neutrophil
dysfunction and
specific bacteria.
Immune
response play
a major role in
maintaining
the integrity of
body tissue.
Thereby more
information is
required on
other immune
responses.
2c
52. There is a great deal of synergy between the
adaptive immune system and its innate
counterpart, and defects in either system can lead
to immunopathological disorders, including
autoimmune diseases, immunodeficiencies and
hypersensitivity reactions.
The remainder of this supplement will focus on the
appropriate diagnosis, treatment and management
of some of these more prominent disorders,
particularly those associated with hypersensitivity
reactions.
