2. Immunology and Immunity
Learning Objectives
•Introduction of basic immunity
•Types of immunity
•Cells involved in the process of
immunity
•Types of immunoglobulins
4. • Structure and function of immune system
• Immune response
• Hypersensitivity
• Autoimmunity
• Oral immunology
Cont….
5. • The term Immunity is derived from the Latin word Immunitae
• Which referred to the protection from the legal
• Prosecution offered to Roman Senators during their tenure
in office
• Refers to the resistance exhibited by the host towards injury
• Caused by microorganisms and their products
IMMUNITY
6. IMMUNITY
• Protection against infectious diseases
• Distinguishes self from non-self
• Eliminate potentially destructive foreign
substances from body
8. INNATE IMMUNITY ACQUIRED IMMUNITY
Resistance to infection which individual
possesses by virtue of his genetic and
constitutional make up
Early defense response against microbes
Immune response Non specific
Innate response do not alter on repeated
exposure
Memory effect absent
Not affected by immunisation or prior contact
The resistance that an individual acquires
during life
Later defense response
Immune response is highly specific
Adaptive response improves with each
successive encounter with same pathogen
Memory effect present
Is improved by immunisation
9. • It consists of cellular and biochemical
defense mechanisms that
• Are in place even before infections and poised
to respond rapidly to infections
• These mechanisms react only to microbes and
not to non-infectious substances
INNATE IMMUNITY
11. Species immunity
"Species immunity," often referred to as "species resistance," is a concept in epidemiology
and immunology that explains why certain pathogens infect some species but not others.
This form of immunity is intrinsic to the species as a whole, rather than to individual
immune responses or acquired immunity that individuals develop after exposure to
pathogens.
Several factors contribute to species immunity, including:
1.Genetic Differences: The genetic makeup of a species can make it inherently resistant to
certain pathogens. For instance, differences in cell surface receptors can prevent pathogens
from binding and entering cells, effectively stopping an infection before it starts.
2.Physiological Factors: Variations in body temperature, pH levels, and the presence of
specific enzymes or biochemical environments can inhibit the growth or activity of
pathogens in certain species.
3.Immune System Characteristics: The innate immune system components, such as physical
barriers (skin, mucous membranes) and internal defenses (white blood cells, cytokines), can
vary significantly among species, offering different levels of protection against pathogens.
12. The reason why certain pathogens infect some species but not others is multifaceted, involving a complex interplay of biological, genetic,
and ecological factors. Here are the key reasons behind this specificity:
Host Cell Receptors: For a pathogen to infect a host, it often needs to bind to specific receptors on the surface of the host's cells. The
presence or absence of these receptors in different species can determine whether a pathogen can effectively attach to and invade cells.
Species lacking the necessary receptors are naturally resistant to those pathogens.
Immune System Differences: The immune systems of different species can vary significantly in their components and responses. Some
species may have innate immune mechanisms or adaptive immune responses that are particularly effective against certain pathogens. This
includes differences in immune signaling molecules, types of immune cells, and the presence of specific antibodies.
Temperature and Physiological Conditions: The body temperature and internal conditions (such as pH levels) of different species can
affect the ability of pathogens to survive and replicate. For example, the body temperature of birds is generally higher than that of
mammals, which can make birds inhospitable hosts for certain viruses that thrive at lower temperatures.
Genetic Factors: Genetic variation among species can influence susceptibility to infection. This includes not only genes directly involved
in immune responses but also those affecting cell structure, metabolism, and overall physiology that can indirectly impact a pathogen's
ability to establish an infection.
Ecological and Behavioral Factors: The ecological niches occupied by different species and their behaviors can influence their exposure
to pathogens. For instance, species that live in close proximity to humans or domestic animals may be more likely to encounter and
potentially transmit zoonotic pathogens.
13. • If one race is susceptible while other race is resistant to
same infection, then it is called Racial immunity. • For
examples; certain African race are more resistant to malaria
and yellow fever where are Asian or Americans are
susceptible to same infection.
Racial immunity
14. • Individual immunity refers to how some individuals in a population are
more resistant to certain types of diseases than others. Certain types of
individual immunity can have various correlated factors, like nutrition,
age, and the influence of certain hormones.
• For examples; Individual with genetic deficiency of glucose-6 phosphate
dehydrogenase are resistant to Malaria.
Individual immunity
15. I. Species and strains
II. Age
III.Hormonal Influences
IV.Nutrition
Determinants of innate immunity
16. • A person is said to be immunewhenhe possesses specific
protective Antibodies or cellular immunity as a result of previous
infection Or immunization or is so conditioned by such previous
experience as to respond adequately to prevent infection ,
Because this form of immunity develops as a response to
infection and is adaptive to the infection, it is called adaptive
immunity
ACQUIRED IMMUNITY
17. • The characteristics of adaptive immunity are
• Specificity for distinct molecules
• An ability to remember and respond more vigorously
to repeated exposure to the same microbe
• Hence it is also called as specific immunity
Cont….
18. ACTIVE IMMUNITY PASSIVE IMMUNITY
1. Produced actively by host’s
immune system
Received passively by the host
2. Induced by infection or by contact
with immunogens (vaccines,
allergens etc).
No participation by the host’s immune system
3. Affords desirable and effective
protection
Conferred by introduction of readymade antibodies
4. Immunity effective only after a lag
period (time required for generation
of antibodies).
Protection transient and less effective
Immunity effective immediately
5. Immunological memory present;
subsequent challenge more
effective (booster effect)
No immunological memory subsequent
administration of antibodies less effective due to
immune elimination
6. Negative phase may occur No negative phase
7. Not applicable in
immunodeficient hosts
Applicable in immunodeficient hosts
19. ⇨ This results from either a clinical or in-apparent infection.
⇨Immunity following chicken pox and measles infection is usually life
long
Artificial Active Immunity
⇨ This is the resistance induced by vaccines.
⇨Vaccines are preparations of live or killed microorganisms or their
products
used for immunization
Natural Active immunity
20. Immunizing agents that are used for
immunoprophylaxis
⇨ Bacterial vaccines:
• Live (BCG vaccine for T.B.)
• Killed (Cholera vaccine)
• Subunit (Typhoid antigen)
• Bacterial products (Tetanus Toxoid)
Types of
Vaccine
22. • 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)
Combinations
23. • 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)
Cont….
24. • This is the resistance passively transferred from the mother to the
baby
• In human infants, maternal antibodies are , transmitted
predominantly through the placenta. Human colustrum, which is
also rich in IgA antibodies and resistant to intestinal digestion.
Natural Passive immunity
25. • Synthesis of antibodies (IgM) occurs at 20th week of IUL
(intrauterine life). But its immunogenic capacity is still
inadequate at birth. It is only by about the age of three
month that the infants.
Cont….
