Immunity is the power to resist and overcome infection caused by particular organism. RESISTANCE EXHIBITED BY THE HOST AGAINST MICROBES AND THEIR PRODUCTS Innate immunity:“Innate” because shared by all animals (Pre-existing/ By birth) and Non-specific Adaptive immunity (Acquired Immunity):Responsive and Specific The immune system recognizes, attacks, destroys, and remembers each pathogen that enters the body. The Immune System includes all parts of the body that help in the recognition and destruction of foreign materials. White blood cells, phagocytes and lymphocytes, bone marrow, lymph nodes, tonsils, thymus, and your spleen are all part of the immune system. prepared by: DR.PRINCE C P HOD & Associate Professor Department of Microbiology Mother Theresa Post Graduate & Research Institute of Health Sciences (Government of Puducherry Institution) Pondicherry

1. IMMUNITY & IMMUNE SYSTEM
DR.PRINCE C P
HOD & Associate Professor
Department of Microbiology
Mother Theresa Post Graduate & Research Institute of Health Sciences
(Government of Puducherry Institution)
Pondicherry

2. Immunity ?
• Immunity is the power to resist and overcome
infection caused by particular organism.
• RESISTANCE EXHIBITED BY THE HOST
AGAINST MICROBES AND THEIR PRODUCTS

3. Types of Immunity
• Innate immunity:“Innate” because shared by
all animals (Pre-existing/ By birth) and Non-
specific
• Adaptive immunity (Acquired
Immunity):Responsive and Specific

6. Factors influencing the immune status of individuals
• Racial: Some races are susceptible or immune to
certain diseases. For example, Hebrews are more
resistant to tuberculosis than other people.
• Species: Some of the species of animals have resistance
to certain diseases. Eg. Lower animals never get
measles or typhoid fever while man is susceptible to
get these diseases. Birds do not get infection with
certain kind of tubercle bacilli, which affects cattle or
man.
• Individual: Some people have a store natural resistance
or immunity to certain disease. This is known as
individual immunity.

7. IMMUNE SYSTEM
• The immune system recognizes, attacks, destroys,
and remembers each pathogen that enters the
body.
• The Immune System includes all parts of the body
that help in the recognition and destruction of
foreign materials.
• White blood cells, phagocytes and lymphocytes,
bone marrow, lymph nodes, tonsils, thymus, and
your spleen are all part of the immune system.

11. Lines of defence
• The immune system protects organisms with
layered defences of increasing specificity.
• 1. physical barriers prevent pathogens such as
bacteria and viruses from entering the body.
• 2. innate immune system provides an immediate,
but nonspecific response.
• If pathogens successfully evade the innate
response, vertebrates possess a third layer of
protection
• 3. adaptive immune system

12. Innate Immunity
• First line of defense /Barriers
• Skin (epidermis and dermis)
• Mucous membranes: respiratory, GI,
genitourinary tracts
• Lacrimal apparatus: tears
• Saliva
• Sebum: acids
• Perspiration: lysozyme
• Gastric juice-acid
• Urine

13. Innate Immunity
• Protection against infection that relies on
mechanisms that exist before infection–
Second line of defence
• Phagocytosis
• Inflammation
• Complement
• Interferon

17. Lacrimal apparatus
• Tear mechanically remove the foreign partical
and also contains, Lysozyme which constantly
baths surface of the eye. (also found with the
female urogenital tract, and saliva)
• Lysozyme breaks the glycosidic bonds
between the NAG and NAM that make up the
backbone of peptidoglycan—causing bacteria
to lyse.

18. Saliva
• Saliva mechanically washes pathogens off
your teeth, and reduces the numberof
pathogens.
• Saliva contain an antibody called secretory
immunoglobulin A, or “SIgA” which coats and
protects every tooth from harmful bacteria
that may cause decay.

19. Phagocytosis

22. Inflammation
• Redness - due to capillary dilation resulting in
increased blood flow
• Heat - due to capillary dilation resulting in
increased blood flow
• Swelling – due to passage of plasma from the
blood stream into the damaged tissue
• Pain – due mainly to tissue destruction and, to
a lesser extent, swelling.

24. Complement system
• 20 different proteins that work together to
destroy to invaders and recruit immune cells
• Activated three different ways
• 1. “Classical” pathway: by antibodies bound to
pathogen
• 2. “Alternative” pathway: by bacterial surfaces
• 3. Lectin activation pathway: by binding of
mannose binding lectin (MBL) to yeast, bacteria,
parasites or viruses (e.g., HIV)
• Activation of complement system is tightly
regulated because end results can be dangerous

25. Complement action

26. Interferon
• Interferon are proteins, immunologist prefer to
call them cytokines
• – They are glycosylated
• The name originates from the fact that they
interfere with viral infection
• Cells producing IFNs
• – Plasmacytoid DCs (major producers of IFN- a
and IFN- b)
• – Fibroblasts and epithelial cells
• – Macrophages and Th1 Cells

28. Acquired immunity
• Acquired immunity may be natural or artificial.
• Acquired artificial immunity: Immunity which is acquired
artificially by introducing vaccine and toxoid (active) and
serum (passive) is known as acquired artificial immunity.
• Acquired natural active immunity: People who suffered
from disease will have immunity against that particular
disease. Eg. Smallpox. This is known as acquired natural
active immunity.
• Acquired natural passive immunity: The child gets
antibodies from its mother through placenta and breast
milk and has immunity for sometime against certain
disease.
• Acquired artificial passive immunity: by antiserum

29. Acquired immunity

30. Acquired immunity
• Characteristics
• Specificity: directed at specific targets
• Systemic: not restricted to initial site of
infection /invasion
• Memory: after initial exposure & activation, a
more rapid & more vigorous response is made
to subsequent exposures to pathogens

31. Adaptive Defences: Components
• Humoral Immunity: (antibody mediated
immunity) provided by antibodies floating free
in body fluids
• Cell mediated immunity: – lymphocytes
directly attack specific invaders by lysis or
indirect attack by initiating inflammation
and/or activating other lymphocytes &
macrophages

34. Antigens vs Antibodies
• Antigens are macromolecules that elicit an
immune response in the body and can
specifically bind with antibody. The most
common antigens are proteins and
polysaccharides.
• Antibody is a “Y” shaped protein produced in
response to an antigen.

35. Types of Immunization
• Active immunization: It implies administration of
antigenic preparation in order to stimulate
production of antibodies within the tissues of the
individual. This is known as active immunity. The
material used for producing active immunity is
vaccines Eg. BCG.
• Passive immunization: Sera containing specific
antibodies are directly injected to produce
passive immunity. Eg. Anti-toxin sera in
diphtheria (prepared from horse serum) and
tetanus immunoglobulins.

36. Vaccines
• a) Live, virulent organism in sub lethal doses
Eg. Cholera vaccine, anti.-rabies vaccine.
• b) Live attenuated organisms. Eg. Vaccine for
smallpox, tuberculosis (BCG) and yellow fever.
• c) Dead (Killed) organisms Eg. Vaccines of
typhoid, cholera and plague.
• d) Toxins of organisms, such as toxoid. Eg.
Vaccines for diphtheria, tetanus and scarlet
fever.

37. Thanks