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SPECIFIC and NON-SPECIFIC IMMUNE RESPONSES

The immune system is composed of two subdivisions: the non specific (innate) immune system and the specific (adaptive) immune system. Each arm of the immune system has both cellular and humoral components by which they carry out their protective function.

Non-specific Immune Response

Specific Immune Response

Response is antigen-dependant

Response is antigen-dependant

There is immediate maximum response

There is a delay between exposure and maximum response

Not antigen-specific

Antigen specific

Exposure results in no immunologic memory

Exposure results in immunologic memory


NON SPECIFIC RESPONSE

The first line of defence is non-specific. The body's external barriers including skin, hair, tears and mucous prevent organisms from entering and invading it.

 

Phagocytes engulf pathogens. Complement proteins destroy pathogens or stimulate phagocytes. Natural Killer cells destroy infected cells. Interferon increases cell resistance to virus invasion. Mast cells release histamines that trigger inflammation.


 

 

 

 


 

 


SPECIFIC RESPONSE

The second line of defence is specific.

 

Antibody mediated

Cell mediated

Site

Body fluids

Infected cells

Cells involved

T helper cells
B plasma cells
B memory cells

T helper cells
T suppressor cells
Cytotoxic T cells

Antibodies involved

Yes

 No

Helper T cells stimulate both B and T cells
B plasma cells produce antibodies
Cytotoxic T cells destroy cells infected by the particular pathogen
Plasma cells secrete antibodies
Macrophages eliminate infected red blood cells
Memory cells provide for immunity by "remembering" the organisms


This graph indicates how the immune system develops a "memory" of the pathogens it has encountered. Antibodies circulating in your blood and the presence of memory cells create an immunity. If you are infected by the same pathogen, they will be ready to multiply and produce large quantity of plasma cells and antibodies to fight against the pathogen. The second immune response is faster and bigger because the antibody destroys the pathogen before any symptoms can appear.

 

 


 

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