Immunology-Antigens

[license2kill]

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What is the true definition of antigen? I thought that antigens were identification markers labeling a foreign molecule as being "foreign". But the word antigen is used when describing blood types which is a "domestic" concept. Then, is an antigen simply a marker protein whether foreign or domestic depending on context? Can someone clarify? 🙂

 

[WayneSU]

antigen is anything that can bind to a receptor on an immune cell....can but doesnt have to activate the cell (immunogen is an antigen that does activate an immune cell)

 

[jdent]

Yes, they can identify something as a foreign body promoting the antibody production to trigger an immune response.

 

[yakuza]

This is correct. They're also either made of proteins or polysacs.

You might also want to know allergy. This is when the body produces antigens in response to the body becoming exposed to an allergon (foods you're allergic to).

 

[WayneSU]

This is correct. They're also either made of proteins or polysacs.

You might also want to know allergy. This is when the body produces antigens in response to the body becoming exposed to an allergon (foods you're allergic to).

yup...here there is nothing wrong with ur immune system, its responding to something foriegn (recognizing the antigen as nonself) but its something that is not harmful to the body and that is why u get an allergic response

 

[osimsDDS]

What is the true definition of antigen? I thought that antigens were identification markers labeling a foreign molecule as being "foreign". But the word antigen is used when describing blood types which is a "domestic" concept. Then, is an antigen simply a marker protein whether foreign or domestic depending on context? Can someone clarify? 🙂

The word antigen is used to describe blood types because every blood group has an antigen, lets take for example type A. Type A has antigen A because if you donate A to B then B will sense that A is a foreign invader because of the antigens on A. Type O doesnt have any antigens therefore it is called the universal donor. Type AB has "AB" antigens but does not have "AB" antibodies therefore it is the universal recipient...It makes sense because if you donate A blood to AB, it doesnt have antigens against its own A or even B blood because remember blood groups are coodominant and both alleles are expressed!