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Introduction to Immunology
Immunity and Types
Dr. P. Srinivasan
Rathinam College of Arts and Science

2. Born on May 17, 1749, in Berkeley, Gloucestershire, England, Died Jan.
26, 1823.
· As a teenager, while learning to be a physician, he heard a young
farm girl tell a doctor that she could not contract smallpox because she
had once had cowpox (a very mild disease). This started him thinking
about a vaccine.
· After years of experimenting, on May 14, 1796, Edward Jenner
carried out a famous experiment on a healthy 8-year-old boy, James
Phipps, with cowpox. He took material from a burst pustule on the arm
of Sarah Nelmes who had apparently contracted cowpox. He then
deliberately exposed the boy to virulent variola virus two months later
and found that the child was protected, showing only a mild
inflammation around the site where the variola was injected.
· Some record shows that in 1789 he had already experimented
vaccination on his own son, then aged one-and-a-half, with the swine
pox, followed by conventional smallpox inoculation.
A CRIME??
Sarah Nelmes’
hand
Edward Jenner
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3. Louie Louie…
1879- discovered that old
bacterial cultures of
Pasteurella lost virulence.
Referred to injection of
weakened culture a
“vaccine” in honor of
Jenner
1881- He applied the same
technique vs. anthrax
….and then rabies
Pasteur inoculating sheep at
Msr. Rossignol’s farm – May,
1881
Louis Pasteur
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4. First insights into mechanics of immunity…
1880’s- Metchnikoff
discovered phagocytic
cells that ingest microbes
and particles
cells conferred immunity
1890- von Behring and
Kitasato discovered blood
sera could transfer
immunity
liquid of blood conferred
immunity
Q: Which confers immunity…
cells or serum?
Emil von Behring
S. Kitasato
Elie Metchnikoff
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5. • 1930’s – early techniques made it easier to
study humoral elements [than cellular
ones].
-discovery of active component of blood –
gamma globulin “protein”
• 1950’s – discovery of T and B cells
Later discoveries linked lymphocytes to
both cellular and humoral immunity
A: Both cells and serum contribute to immunity!
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6. Understanding specificity of antibody for antigen took years
• Early 1900’s- Landsteiner
revealed antibody could be
produced vs. most any organic
compound
• Last 20 yrs- Antibody specificity
reveals unlimited range of
reactivity – also to newly
synthesized chemicals!
Karl Landsteiner
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7. Louis Pasteur (1822-1895)
• Stereochemistist: molecular asymmetry
• Fermentation and silk worker disease
• Germ Theory of disease
• Attenuated vaccines for cholera, anthrax, and rabies
• On July 4, 1886, 9-year-old Joseph Meister was bitten repeatedly by a
rabid dog. Pasteur treated him with his attenuated rabies vaccine two
days later. Meister survived.
• Joseph Meister later become a gatekeeper for the Pasteur Institute.
In 1940, when he was ordered by the German occupiers to open
Pasteur's crypt, Joseph Meister refused and committed suicide!
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8. · Awarded first Nobel Prize in physiology, 1901
· Student of Koch
· With Kitasato and Wernike, discovered anti-
toxin for Diphtheria and Tetanus and applied as
therapy.
Emil Adolf von Behring (1854 – 1917)
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9. Developed a series of tissue-staining dyes including that for tubercle bacillus.
· Worked with Koch. Developed anti-toxin (Diphtheria) and hemolysis
· Side-chain theory of antibody formation:
"surface receptors bound by lock & key; Ag stimulated receptors"
· Shared 1908 Nobel Prize with Metchnikoff.
Paul Ehrlich (1854 – 1915)
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10. • Formed the basis of leukocyte phagocytosis.
• Birth of cellular immunology
• Shared Nobel Prize with Ehrlich in 1908
Elie Metchnikoff (1845-1916)
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11. Milstein (b. 1927) and Köhler (1946-1995)
· Monoclonal antibody
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12. • Cloning of the Immunoglobulin gene
• 1987 Nobel prize for his discovery of "the genetic principle for generation of antibody
diversity".
Susumu Tonegawa (b. 1939)
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13. • Two signals
• 1996 Nobel Prize for their discoveries concerning "the specificity of the cell-mediated
immune defense".
Peter C. Doherty and Rolf M. Zinkernagel
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14. Cells of the Immune System
• All the cells of the Immune System are
leucocytes and originate in the bone marrow
from a common precursor, the pluripotent
stem cell.
• Some cells are mature when they leave the
marrow.
• Other cells complete their differentiation
outside the marrow.
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• Immunology (Latin- Immunis- protect from) is the study of host defence
mechanisms.
• Immunity is the ability of the host to protect itself against foreign
organisms.
• The immune system comprises the tissues, cells & molecules which mount
the immune response.
• Any substance that elicits an immune response is called Antigen (Ag) or
Immunogen or Allergen.
• Proteins that are produced from host that acts against the antigen is called
an Anti-body (Ab).
• WBCs- White Blood cells or Leukocytes are cells produced by host to
protect against pathogen invasion.
Definitions

16. IMMUNITY
• The term immunity refers to the resistance exhibited by the host
towards infection caused by micro organisms and their
products(toxins).
• This is based on the property of self and non self recognition. That
means immunity is carried out by the process of recognition and
disposal of non self or materials that enter the body.
• Immune response is the reaction of the body against any foreign
antigen.
• But protection against infection disease is only a part of it.
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18. Innate immunity
• It is comes because of genetic and constitutional make up.
• It has no relation ship with previous bacterial infection and immunization.
• It acts as first line of defense against infections, micro organisms, their products
before they cause disease.
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• The various non specific defense mechanisms are present.
1. anatomical and physical barriers.
2. physiological and chemical barriers.
3. biological barriers.
4. general barriers.

19. Physiological and chemical barriers
• The barriers prevent the entry of pathogens to
resist infection.
• These include
Ex; skin, mucous membrane, coughing and
sneezing, etc.
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20. Skin
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21. Mucous Membrane
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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.

22. Physiological and chemical barriers
• Human milk: this is very rich in anti bacterial substances.
Ex: Ig A, lacto feritin, neuraminic acid etc. they fight against E.
coli and Staphylococci.
• Secretion of the digestive tract: stomach as 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:
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23. 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 comanly divided in to 2 types.
1. Phagocytosis.
2. Pinocytosis.
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25. 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:
• Individual immunity:
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26. Acquired immunity
• The acquiring of immunity from out side source is known as acquired
immunity.
• It is result of action of 2 major groups of cells.
1.lymphocytes
2.antigen presenting cells
This immunity is initiated by the recognition of a foreign antigen and the
response to this recognition.
It is highly adaptive and has 4importent features.
1.antigen specificity.
2.diversity.
3.immunological memory.
4.recognition self from non-self.
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28. 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.
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29. Action of lymphocytes and Apcs
• Lymphocytes:they poses antigen binding cell surface receptors.
• Antigen presenting cells: they have class-2 MHC on their
surface and they present anti gens to lymphocytes.
• This immune response is of 2 types
1. humoral immune response
2. cell mediated immune response.
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30. Passive immunity
• Acquiring of the antibodies passively from an immunized donor
to a non-immunized recipient is noun as passive immunity.
Natural passive immunity: it occurs when anti bodies are
transferred from the donar to the recipient in a natural manner.
Ex: Transfer of anti bodies from the mother to the foetus
through the placenta (IgG Antibodies)
Artificial passive immunity: the transfer anti bodies and
sensitised lymphocytes from immunized donar to the non-
immunized recipient artificially.
Ex: antibodies produce in the horse serum and
GMOS(genitically modified organisms).
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