Acquired Immunity

Acquired Immunity Dr. Mejbah Uddin Ahmed

WELL COME

Adaptive (acquired) immunity  Adaptive

(acquired) immunity refers to antigen-specific defense mechanisms that take several days to become protective and are designed to remove a specific antigen This is the immunity one develops throughout life.

Adaptive (acquired) immunity

Acquired immunity is acquired after exposure to foreign substance and is exquisitely specific. It supplements and amplifies the protection offered by innate immunity.

Acquired immunity Crieteria of acquired immunity: 

Specific 3rd Line of Defense.



Like snipers in the military they have a specific target i.e. Antigen specific.



Mediated by lymphocytes: key cells of the

acquired immune response. 2

main types of lymphocytes:

• 80% T cells (cell mediated). • 15% B cells (antibody mediated).

Acquired immunity  Crieteria

of acquired immunity:

Efficient and selective immune responses  Systemic – not restricted to the initial infection site  Has memory – recognizes and mounts a stronger attack on previously encountered pathogens 

Classification of Immunity

Acquisition of Acquired Immunity Can be acquired naturally or artificially: Natural acquisition—person acquires immunity through natural means: Active & Passive.  artificial acquisition—person is given something that results in immunity: Active & Passive. 

Acquisition of Acquired Immunity A.Naturally Acquired Active Immunity:  Antigens or pathogens enter body naturally.  Body generates an immune response to antigens.  Immunity may be lifelong (chickenpox or mumps) or temporary (influenza or intestinal infections).

Acquisition of Acquired Immunity B. Naturally Acquired Passive Immunity:  Antibodies

pass from mother to fetus via placenta or breast feeding (colostrum).  No immune response to antigens.  Immunity is usually short-lived (weeks to months).  Protection until child’s immune system develops.

Acquisition of Acquired Immunity 1.Artificially acquired active immunity:  Antigens

are introduced in vaccines (immunization).  Body generates an immune response to antigens.  Immunity can be lifelong (oral polio vaccine) or temporary (tetanus toxoid).

Acquisition of Acquired Immunity 2.Artificially acquired passive immunity:  Preformed antibodies (antiserum) are introduced into body by injection: ATS or TIG

 Immunity

is short lived (half life three

weeks).  Host immune system respond to antigens.

does

not

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