cell recognition

what are on the surface of antigens?

antigens have specific proteins on their surface which allow the immune system to recognize and respond to different types of cells or substances

what can the immune system identify? (self from non self cells)

• pathogens - have foreign antigens which trigger an immune response

• cells from other organisms of the same species - recognised as foreign which leads to rejection

• abnormal body cells - have different antigens which allows immune cells to detect them for destruction

• toxins - recognised as harmful molecules

antigen definition

a protein found on the surface of cells that is recognised by the immune system & triggers an immune respones

antigen variability & effect of disease prevention

pathogens can undergo antigenic variation, e.g by mutation, where changes in their surface antigens make them unrecognisable to the immune system.

• This can lead to re-infection because the immune system can’t recognize the new antigens

Effect on Disease Prevention:

• Vaccines may become less effective if pathogens undergo significant antigenic variation, requiring annual updates (e.g., flu vaccine).