1. Antigens Flashcards
What are antigens?
Molecules that can generate an immune response when detected by the body.
Usually found on the surface of the cells.
Antigens that aren’t normally found in the body are called foreign antigens.
What do antigens allow the immune system to identify?
Pathogens.
Abnormal body cells.
Toxins.
Cells from other individual’s of the same species.
What are pathogens?
Organisms that cause disease eg bacteria, fungi, viruses.
They have antigens on their surfaces they are identified as foreign by the immune system cells, which then respond by destroying the pathogen.
What are abnormal body cells?
Cancerous or pathogen-infected cells have abnormal antigens on their surface, which trigger an immune response.
What are toxins?
Poisons - molecules - not cells.
Some produced by bacteria.
Immune system can respond t them as well as the pathogen that released them.
Give an example of a toxin?
The bacterium Clostridium botulinum releases a protein toxin that affects the nervous system casuing systems of botulism.
What does it mean by ‘cells from other individuals of the same species’?
Receiving cells from another person, organ transplant or blood transfusion, those cells have different antigens that are different to your own.
Foreign antigens trigger immune response which rejects transplanted organs if drugs aren’t used to suppress the recipients immune system.
What happens in blood transfusions?
Most important antigens are the ABO blood group antigens.
If donated blood contains A or B antigens that aren’t recognised by the recipient’s immune system they will generate an immune response.
What do toxins not have?
Antigens on their surface as they are an antigen itself.
The ABO blood groups are…
A
B
AB
O
Type A blood has…
A antigens on its red blood cells.
Type B blood has…
B antigens.
Type AB blood has…
Both A and B antigens.
Type O blood has…
No A or B antigens.
If a person has type B blood their immune system won’t recognise type A antigens.
