A presentation on immunity to infection by Mohammed Yasidi Bularafa.

1. IMMUNITY
YASIDI. M. B

2. IMMUNITY
• The term “immunity” refers to the
resistance exhibited by an individual or
the host toward an infections caused by
microorganisms and their products
(toxins)
• This is based on properties of self and
non-self recognition, because immunity
are carried out by the process of
recognition or disposal of non-self.

3. TYPES OF IMMUNITY
• Immunity against infection are of two (2) types:-
A. Innate or native immunity
B. Adaptive or acquired immunity
A. Innate or native immunity:- This can be either:-
1. Specific immunity
 Species immunity
 Racial immunity
 Individual immunity

4. TYPES OF IMMUNITY
2. Non-specific immunity:-
 Species immunity
 Racial immunity
 Individual immunity
B. Adaptive or acquired immunity
1. Active immunity (Natural and passive)
2. Passive immunity (Natural and passive)

5. TYPES OF IMMUNITY

6. TYPES OF IMMUNITY

7. INNATE IMMUNITY
• This is the first line of defence against infections
• Not affected by prior contact with infectious microorganisms or
by immunizations
• Specific (resistance to a particular pathogen)
• Non-specific (general degree of resistance to infections)
• Species immunity:- .E.g Resistance to plant pathogens,
mechanism still unclear, it determine whether or not organism
multiply in them all or relative refractoriness to a pathogens
• Racial immunity:- E.g. Algerian sheep resistance to Anthrax,
Afri-Amerian more susceptible to TB than Caucasians,

8. INNATE IMMUNITY
• Individual immunity:- E.g. Twins resistance or susceptible to
lepromatous leprosy
• Mechanism of innate immunity
a. Epithelial surface:- Intact skin, mucosal membranes, mechanical
barrier, bactericidal activity (high salt, drying, sebaceous secretions,
long chain fatty acid) nasal mucosa, saliva, gastric acid, flushing
action of lacrimal secretions, lysosome in tears, flushing actions of
urine, spermine and zinc in sperm has antibacterial effects, acidity of
adult vagina due to glycogen fermentation in epithelial cells by
resident acid uric lactobacilli makes it inhabitable for most organisms

9. b. Antibacterial substances in the blood and tissues:-
 Betalysin:- active against anthrax and related bacilli
 Polypeptides:- like leukins and plakins from leukocytes
 Acidic substances:- lactic acid in tissues, lactoperoxidase in milk
 Microbial antagonism:- skin and mucous membrane has resident
commensal bacterial flora
c. Cellular factors:-
 Phagocytes:
d. Inflammations
 Fever
 Toll-like receptors

10. ADAPTIVE IMMUNITY
• Also known as acquired immunity
• Antigenic specificity
• Diversity
• Immunological memory
• Self/non-self recognitions
Types Of Adaptive Immunity
1. Active immunity
2. Passive immunity

11. ADAPTIVE IMMUNITY

12. ACTIVE IMMUNITY
• Functioning immune system: B-lymphocytes for
antibody production and stimulations of other
immunological cells.
• Once developed is long-lasting
• Second immune response is rapid
• Both CMI and humoral immunity developed;
immunological memory is present.
• Active immunity more effective and confers
protection than passive immunity. Resistance
developed by individual as a result of antigenic
stimulus.

13. Natural Active Immunity
• Clinical or in apparent infection by microbes.
• Patient recovered from attack developed natural active immunity
• Immunity is lifelong as in chicken pox, and measles.
• Influenza or common cold; short-lived and can reoccur.
Artificial Active Immunity
• Resistance induced by vaccine, such as
 Bacterial vaccine: live-BCG, killed- cholera, subunit- typhoid Vi
antigen, bacterial products- Tetanus toxoids.
 Viral vaccines: live- Sabin or oral polio, killed- Salk or
injectable polio, subunit- Hepatitis vaccines.

14. PASSIVE IMMUNITY
• No active role from Host’ from immune system.
• No need for antigenic stimulation preformed antibodies are
administered.
• No latent period, immediately after administration it gives
active protection
• Immunity is transient, lasting for days or weeks.
• Less effective, acts immediately so it provides instant immunity
• Resistance is transmitted passively to a recipient in a ready
made form.

15. TYPES OF PASSIVE IMMUNITY
• Natural passive immunity:- This is an immunity passively
transferred from Mother to offspring , maternal antibody are
transferred through placenta, human colostrum is rich in IgA
• Artificial passive immunity:- This is an immunity passively
transferred via administration of prepared antibodies
• Hyperimmune serum of human or animal
• Convalescent sera
• Pooled human gamma globulin
• Equine gamma globulin (ATS)
• Human hyperimmune globulin
• Animal preparation (antisera)

16. ACTIVE IMMUNITY PASSIVE IMMUNITY
a. Produced actively by the host’s immune
system
a. Received passively no active participation of
the host’s immune system
b. Induced by infection or immunogen b. Ready made antibody is transferred
c. Durable and effective protection c. Transient, less effective
d. Immunity effective after lag phase d. Immediate immunity
e. Booster has effect on subsequent dose e. Subsequent dose less effective
f. Presence of immunological memory f. No immunological memory
g. Not applicable in the immunodeficient g. Applicable in immunodeficient

17. IMMUNOPROPHYLAXIS
• Immunoprophylaxis is the
prevention of disease by the
administration of vaccine or
hyperimmune sera or
prevention of disease by
producing active or passive
immunity.
Immunization:- Is the
process where by a person is
made immune or resistant to
an infectious disease, typically
by administration of vaccines.

18. HYPERSENSITIVITY
• This is an exaggerated immune
response that results in tissue
damages and is manifested in an
individual on a second or
subsequent exposure to the
antigen.
Types of hypersensitivity
1. Immediate hypersensitivity
2. Delayed hypersensitivity

19. TYPES OF HYPERSENSITIVITY
IMMEDIATE DELAYED
a. Reaction appears immediately
within minute and recedes usually in
an hour
Appear slowly within 24-72hrs and
last longer for days
b. Antibody mediated reactions Cell mediated
c. Passive transferred by serum or their
extract
Transfer only with lymphoid cells
d. Desensitization is easy but short-live Difficult but long lasting
e. Wheal and flare with maximum
diameter in 6hrs
Erythema and induration with
maximum diameter in 24-48hrs

20. TYPE I HYPERSENSITIVITY
• Also known as anaphylactic reaction
which denote a severe manifestation
of allergic reactions.
• It is an IgE mediated reactions that
occurs quickly when a large
shocking dose of antigen is
introduced after one or more small
dose of sensitization.
• Characterized as : immediate, last for
few second to minutes, occurs due to
increase in vascular permeability,
short duration and not heritable. But
can be localized or systemic.

21. TYPE II CYTOTOXIC REACTION
• This is mediated by IgG, IgM,
antibodies directed toward antigen on
a cell’s surface or other tissue
components which eventually result in
cell damage.
• Antibodies are produce against
antigen that can be microbial products
absorbed on cell’s surfaces or drugs.
• Both IgG and IgM are produced in
type II reaction
• Example ; isoimmune, autoimmune,
drug reactions.

22. TYPE III IMMUNE COMPLEX
REACTION
• This involve formation of
immune complex.
• The complex are phagocytosed
by monocytes or macrophages.
• In the presence of excess
amount of soluble antigens, the
antigen-antibody complexes
may not be removed and this
lead to an inflammatory
response in the body.

23. TYPE IV DELAYED REACTION
• This is delayed type of reaction
that involves cell mediated
immune response.
• The major factor in type IV
reaction is the time required for T
cells to migrate and accumulate
at or near the infection site or
near the antigen.

24. TYPE V STIMULATORY REACTION
• This is a modification of type II
where complexes are formed on
the surfaces of cell, here
proliferation and differentiation
occur instead of killing.
• Such antibodies produced in this
reaction are non-complement
fixing and complexes enhances the
functional activity of affected cells.
E.g. graves disease (where thyroid
hormones are produced in excess)

25. TYPE VI ANTIBODY DEPENDENT CELL
MEDIATED CYTOTOXICITY
• This is mediated through
natural killer cells
• The target cells coated
with concentration of
antibody are killed by NK
cells through extracellular
non-phagocytic
mechanism.

26. AUTOIMMUNITY
• This is a condition that occurs
when the immune system
mistakenly attacks and destroys
self healthy tissues instead of
non-self.
• This is characterized by the body
or immune system producing
antibodies against itself.

27. THANKS