Immunity we acquire as a result of Infection/ Vaccinaion

1. Dr.Riyaz Sheriff M.D ….

2. IMMUNITY
IMMUNITY
INNATE
NON
SPECIFIC
SPECIES
RACE
INDIVIDUAL
SPECIFIC
SPECIES
RACE
INDIVIDUAL
ACQUIRED
ACTIVE
NATURAL
ARTIFICIAL
PASSIVE
NATURAL
ARTIFICIAL

3. ACQUIRED IMMUNITY
• Immunity which a person acquired during his
lifetime
• Not related to innate immunity

4. Acquired IMMUNITY
ACQUIRED
ACTIVE
NATURAL ARTIFICIAL
PASSIVE
NATURAL ARTIFICIAL

5. Acquired active
IMMUNITY
ACQUIRED
ACTIVE
NATURAL ARTIFICIAL
Resistance developed as a result of
antigenic stimulus
Also called “Adaptive Immunity”
Active involvement of host immune
apparatus
Leads to production of antibodies /
Immunologically active cells
Takes time to set in after infection

6. Acquired active
IMMUNITY
ACQUIRED
ACTIVE
NATURAL ARTIFICIAL
Initial NEGATIVE PHASE : The
level of measureable immunity is
lower than it was before exposure to
antigen.
The antigen combines with the
existing antibody leading to reduction
in existing levels of antibody.

7. Acquired active IMMUNITY
ACQUIRED
ACTIVE
NATURAL ARTIFICIAL
Once active immunity sets in
It is long lasting
One second exposure to same antigen the
immune response is quick and abundant
:SECONDARY RESPONSE
Development of humoral & cellular
immunity
Immunological memory
Active immunization is more effective and
confers better protection
May be Natural or Artificial

8. Natural active IMMUNITY
 May be as a result of clinical or inapparent infection
 Measles infection gives the patient life long immunity
 Adults in developing countries have natural active immunity against
polio because of inapparent infections in childhood
 Duration of immunity depends on the pathogen
 Short term – Eg. Influenza
 Long term - Eg. Measeles , chicken pox
 Why common cold does not provide us immunity ???
Antigenic
variation

9. natural active IMMUNITY
 Bacterial infections provide with less degree of
immunity
 PREMUNITION – Seen in syphilis . The immunity to
reinfections lasts only till the original infection is
active.
 Chancroid does not provide the person with any
immunity . Person may develop lesions following
reinfection even when original infection is active.

10. Artificial active immunity
• Resistance induced by vaccines
• Vaccines are preparations of live or killed
microorganisms or their products used for
immunization
• Bacterial vaccines
– Live : BCG vaccine
– Killed: Cholera vaccine
– Subunit : Typhoid Vi antigen
– Bacterial products: Tetanus toxoid
• Viral vaccines
– Live : OPV-Sabin
– Killed : IPV – Salk
– Subunit : Hepatitis B Vaccine

11. Vaccines
LIVE VACCINES
• Infection without disease
• Immunity lasts for several
years
• Booster doses MAY BE
needed
• Can be given orally or
parenterally
KILLED VACCINES
• No infective stage
• Less immunogenic
• Repeated doses needed
– Primary dose
– Booster dose
• Oral doses not effective
• Parenteral doses given with
adjuvant to increase
humoral immunity

12. Passive immunity
o No infection
o Readymade antibodies are
administered
o No latent period
o No negative phase
o Immediate protection
o Immunity lasts for short
duration till antibodies are
metabolized
o No secondary response
o Passive immunity decreases
with repetition

13. Types of passive acquired
immunity PASSIVE
NATURAL ARTIFICIAL
Resistance transferred from mother to baby
Via placenta
Breast milk – colostrum – IgA
IgM production by fetus can start from 20th week of intrauterine life
Inadequate immunity at birth
By 3 months of age – immunological independence
• < 3 months – Pediatric infections are common
Active immunization of mother provides passive immunity to infants
Eg. Tetanus toxoid during pregnancy

14. Types of passive acquired
immunity PASSIVE
NATURAL ARTIFICIALResistance transferred by
administration of antibodies
Hyper immune sera
Convalescent sera
Pooled human Ɣ globulin
Used for prophylaxis and therapy

15. Hyperimmune sera
• Anti-tetanus serum (ATS)
• Prepared from hyperimmunized horses
• Temporary protection
• Disadvantages
• Hypersensitivity
• Immune elimination
• In use
– Hyperimmune globulin of human origin
Animal origin in use
Anti-Gas gangrene sera
Anti-Botulinum sera
Antivenoms

16. Convalescent sera
• Sera of patients recovering from disease
• Contain high levels of antibody specific to the disease
• Use – Viral infections like Hepatitis A
Pooled human Ɣ globulin
• Ɣ globulin from pooled sera of healthy adults
• Has antibodies to all pathogens prevalent in the area
• Use – Rx of patients with immunodeficiencies

17. Indications for passive
immunization
• Immediate and temporary protection of a
person at risk of developing infection
• To arrest overactive active immunity
Eg. Rh incompatibility

18. Combined immunization
• Combination of active and passive methods
• Passive immunization for immediate
protection
• Tetanus
• TIG in one arm + TT in other arm
• Followed by complete schedule of tetanus
vaccination

19. Adoptive immunity
• Special type of immunization
• Injection of immunologically competent
lymphocytes  TRANSFER FACTOR
• Tried in treatment of Lepromatous Leprosy

20. Local immunity
• Besredka
• Treatment of infections in a localized area
• Polio –
– Systemic immunity by IPV
• Does not prevent multiplication of virus in the gut
– This is achieved by OPV
• Influenza
– Killed vaccine brings about a humoral response
• Not enough to prevent infection
• Intra nasal live virus injection/ natural infection provides
local immunity
– IgA

21. Immunoglobulin A (IgA)
• Secretory IgA
• Produced locally by plasma cells on mucosal
surfaces / Secretory glands
• With exposure to an antigen
Specific IgA is produced
• Mucosal defense
• Handling of antigens contracted from food and
external environment

22. Herd immunity
 Overall immunity in a community
 Useful in control of epidemics
• When LARGE NUMBER of people in a community are
immune to a specific pathogen Herd immunity is
SATISFACTORY
• Eradication of communicable disease lies in development of
good herd immunity rather than developing individual
immunity

23. Measurement of immunity
• Practically not possible to measure accurately
• Simple method is to demonstrate the presence of a
specific antibody
– Not reliable as one pathogen will illicit immune response to
multiple antigens
• Antibody demonstration
– Agglutination
– Precipitation
– Complement fixation
– Hemagglutination inhibition
– Neutralization
– ELISA

24. • If antigenic component is identified in-vitro or
in-vivo assays can be done.
• If immunity is associated with cell mediated
immunity
– Skin tests for delayed hypersensitivity
– In-vitro tests for Cell mediated immunity
Measurement of immunity