THE NATIONAL COLLEGE

BASAVANGUDI

THE NATIONAL COLLEGE BASAVANGUDI

THE DEPARTMENT OF ZOOLOGY
SEMINAR

TOPIC:
IMMUNOLOGY
PRIMARY AND SECONDARY
IMMUNITY
PRESENTED BY, IMMUNIZATION
NAME: RASHMI S HYPESENSITIVITY
AUTO-IMMUNE DISEASES
 WHAT IS IMMUNITY?
Immunity is resistant to infection after a foreign antigen has
penetrated the first line of defence.
It is nothing but resistance to disease causing organism or
substance.
It is overall ability of host organism to fight
against the disease causing organisms.

Types of immunity:
1. Active immunity
2. Passive immunity
 ACTIVE IMMUNITY PASSIVE IMMUNITY

Exposure to a disease organism triggers the When a person is given antibodies to a

immune system to produce antibodies to disease rather than producing them
that disease. Active immunity can be through his or her own immune system.
acquired through natural immunity or The major advantage to passive immunity
vaccine-induced immunity. if an immune is that protection is immediate, whereas
person comes into contact with that disease active immunity takes time (usually
in the future, their immune system will several weeks) to develop. However,
recognize it and immediately produce the passive immunity lasts only for a few
antibodies needed to fight it. Active weeks or months. Only active immunity is
immunity is long-lasting, and sometimes long-lasting.
life-long.
 DEFENSE AGAINST DISEASES
Micro-organisms are all around us. As they are not visible
through our naked eyes we don't give them much
importance. Many of the micro-organisms are harmless but
some of them are pathogens.
They cause various diseases and a lot of harm if they enter
into our body.
The body has number of barriers that restrict the entry of
micro-organisms. They can be divided into:
1. Mechanical barriers
2. Physiological barriers
3. Phagocytic barriers
4. Inflammatory barriers
SOME BARRIERS THAT RESTRICT THE
ENTRY OF MICRO-ORGANISMS
 IMMUNE RESPONSE
There are two types of immune responses:

Humeral immune response or humeral immunity

Term ‘humor' refers to the fluid in the body.
The humeral immune response aims at elimination of
pathogens that are extra cellular or seen in the plasma or
tissue fluid. This is achieved by production of antibodies
that
are specific for the antigen. The antibodies that are
produced are in the blood stream and specifically in the
plasma.
Cell-mediated response or cellular immunity
Cell mediated response involves the intact cells to
recognize and eliminate the pathogens that live inside the
host cell. The antibodies produced by the humeral response
cannot reach into the cell. The microorganisms like virus,
etc... live inside the host cells.
 WHAT IS IMMUNE SYSTEM?
Immune system is a large network of organs, white blood
cells, proteins (antibodies) and chemicals.
This system works together to protect you from foreign
invaders (bacteria ,viruses, parasites, and fungi) that cause
infection, illness and disease.
 PRIMARY IMMUNE RESPONSE
/IMMUNITY
 Primary Immune Response is the reaction of the immune
system when it contacts an antigen for the first time.
 There is the activation of T-cells to produce lymphokinins,

the helper and killer cells come to action.

 The B-cells gets differentiated into effector cells and

memory cells.
 The effector cells produce antibodies.
 A sequence of events takes place to fight against the
infection.
 It appears mainly in the lymph nodes and spleen.
 First encounter with an antigen produce humeral response

which involves in production of antibodies.

 The antibody level reaches its peak in 7-10 days.
 It has low affinity towards their antigens.
 Both thymus-dependent and thymus-independent antibodies

are involved in the primary immune response.

 Lag Phase is long (4-7 days),the duration of lag phase varies

depending on the nature of antigen.

 Only few antibodies are produced in the primary immune

response.
 It is due to Immunoglobulin-M (IgM)
 Antibody level declines to the point where it may be

undetectable.
 The primary immune response is usually weaker than

secondary immune response.

 SECONDARY IMMUNE RESPONSE/IMMUNITY
 Secondary Immune Response is the reaction of the
immune system when it contacts an antigen for the
second and subsequent times.
 Appears mainly in the bone marrow and then, in the

spleen and lymph nodes.

 This occurs in response to the second and subsequent

exposure to the same antigen.

 The antibody level reaches its peak in 3-5 days.
 Antibodies show high affinity to their antigens.
 Memory B cells are the responding cells.
 The lag phase is short (1-4 days).
 100-1000 times more antibodies are produced in the

secondary immune response.

 It is due to Immunoglobulin-G (IgG)
 The antibody level tends to remain high for longer.
 The secondary immune response is stronger.

In brief, when B and T-cells replicate during

the primary immune response, they produce effector
cells and long-lived memory cells. Memory B and T-
cells are antigen-specific and, on encountering the
antigen again, can mount a more rapid and effective
immune response, known as the secondary immune
response.
Graph showing the difference in antibody production between the
primary and secondary immune response
 ACTIVE AND PASSIVE IMMUNIZATION
Immunization is providing artificial immunity by
vaccinations.
PASSIVE IMMUNIZATION
 Passive artificial immunization is seen when a person is

injected with ready-made antibodies produced by another

mammal like a horse or a guinea pig.
 This injection of antibodies will confer immediate

protection against any antigen that has entered, such as in

the case of a dog bite or snakebite.
 This immunization is temporary or short lived.
ACTIVE IMMUNIZATION
 If person is injected with a vaccine the active immunity

developed is called artificial immunity.

 Vaccinations are given to develop immunity without a

symptomatic primary infection. The basic principal behind

vaccination is the introduction of an antigen.
 Monoclonal antibodies are used to match the antigens of

the donors and recipients before a transplant is done.

 Monoclonal antibodies are also used to suppress the

action of T-cells to prevent graft rejection.

 HYPERSENSITIVITY
o Hypersensitivity reactions are an overreaction of the immune
system to an antigen which would not normally trigger an immune
response.
o Hypersensitivity can be defined as where the person shows severe

symptoms that can be fatal.People are hypersensitive or show allergic

reactions.
o Term for hypersensitivity is allergy.
o Many drugs, foodstuffs and even simple things as dust and pollen

causes allergies.
o They occur immediately within few minutes or hours when a person

encounters the antigen.

o The allergic reactions occurring due to cellular response is called

delayed hypersensitivity as the reactions take a longer time for the

symptoms to be seen.
o There are 4 types of hypersensitivity.
 TYPE I HYPERSENSITIVITY
 It is immunoglobulin-E mediated.
 Caused due to common allergens like food stuffs, dust,

micro-organisms, venom, pollen, etc...

 Plasma cells release IgE. They bind to mast cells and blood

basophils. A second encounter with antigen causes cross-

linking of IgE molecules, triggering degranulation.
 There will be release of primary and secondary mediates

like histamine and prostaglandins.

Effects: Vasolidation, permeability of blood vessels,
contraction of smooth muscles, constriction of bronchi,
redness of skin, excess mucous production and anaphylactic
shock.
 TYPE II HYPERSENSITIVITY
 It is antibody mediated.
 Caused due to: blood transfusion reaction due to
mismatched blood group, Rh factor incompatibility,
organ transplants, and drug reactions.
 Antibodies can mediate destruction of the cells by
activating the complementing system.
 The cytotoxic cells with Fe receptors bind to the
region of antibodies on target cells and bring
about their destruction.
Effects: transfused blood cells will be broken
down, haemolytic jaundice, phagocytic attack by
killer cells, anaemia.
 TYPE III HYPERSENSITIVITY
 It is immune complex mediated.
 Caused due to: insect bite, bacterial and fungal spores,

dried birds faecal proteins, anti-serum.

 Antibodies are produced against any antigen, these two

combine to form insoluble immune complex.

 Degranulation takes place and tissues are damaged.

Effects: erythema, alveolitis fever, weakness,

rashes,arthritis,
kidney failure, etc..
 TYPE IV HYPERSENSITIVITY
 Delayed type of hypersensitivity.
 Caused due to: exposure to certain bacteria, virus and

fungi, certain chemicals and transplanted tissues.

 Reaction is not immediate and takes some time.
 The helper T-cells secretes cytokines that causes a local

inflammatory reaction.
Effects: Skin shows edema and micro-vesicle formation.
Redness, swelling and warmth.
 AUTO-IMMUNE DISEASES
 An autoimmune disease is a condition in which your
immune system mistakenly attacks your body.
 The immune system normally guards against germs like

bacteria and viruses. When it senses these foreign invaders,

it sends out an army of fighter cells to attack them.
Normally, the immune system can tell the difference
between foreign cells and your own cells.
 In an autoimmune disease, the immune system mistakes

part of your body, like your joints or skin, as foreign. It

releases proteins called autoantibodies that attack healthy
cells.
ORGAN SPECIFIC AUTOIMMUNO DISEASES

These are the diseases where only specific organs are

affected. This is due to the fact that the immune response is
directed specifically at the antigen seen only in that
particular tissue of the organ. The organ may either be
destroyed and fail to function or it may show excessive
functioning.
Examples:
1. Hashimoto’s disease
2. Insulin dependent diabetes mellitus
3. Myasthenia gravis
Hashimoto’s disease
Thyroid hormone production slows to a deficiency.
Symptoms include weight gain, sensitivity to cold, fatigue,
hair loss, and swelling of the thyroid gland.
Myasthenia gravis
It affects nerve impulses that help the brain control the
muscles. When the communication from nerves to muscles
is impaired, signals can’t direct the muscles to contract.
The most common symptom is muscle weakness that gets
worse with activity and improves with rest. Often muscles
that control eye movements, eyelid opening, swallowing,
and
facial movements are involved
Hashimoto’s Disease

Myasthenia gravis
Insulin dependent diabetes mellitus
The pancreas produces the hormone insulin, which helps
regulate blood sugar levels. In Type 1 diabetes mellitus, the
immune system attacks and destroys insulin-producing cells
in the pancreas.
High blood sugar results can lead to damage in the blood
vessels, as well as organs like the heart, kidneys, eyes, and
nerves.
 SYSTEMIC AUTOIMMUNE DISEASES
Occurs when the T-cells and B-cells become hyperactive
due to defect in regulation of the immune system.
Both humeral and cell mediated responses cause
destruction of tissues by production of autoantibodies and
immune complexes.
This affects many organs.
Examples:
1. Multiple sclerosis
2. Rheumatoid arthritis
3. Systemic lupus erythromatosus
Multiple sclerosis
Damages the myelin sheath, the protective coating that
surrounds nerve cells, in your central nervous system.
Damage to the myelin sheath slows the transmission speed
of messages between your brain and spinal cord to and
from the rest of your body.
This damage can lead to symptoms like numbness,
weakness, balance issues, and trouble walking. The disease
comes in several forms that progress at different rates.
Rheumatoid arthritis
The immune system attacks the joints. This attack causes
redness, warmth, soreness, and stiffness in the joints.
Systemic lupus erythtomatosus
It was considered as skin disease because of the rash it
commonly produces, then the systemic form, which is most
common, actually affects many organs, including the joints,
kidneys, brain, and heart.
Joint pain, fatigue, and rashes are among the most common
symptoms.
 REFERENCES
 Introductory Zoology by C.M. Vimala

www.teachmephysiology.com

www.microbenotes.com

www.healthline.com
THANK YOU