Antigens

• What are Antigens?

  • Antigens are molecules (usually proteins) that can generate immune response when detected by the body
  • Usually found on the surface of cells
  • Antigens are not found in the body they called foreign antigens
• What do antigens allow the body to identify?

  Allow the body to identify

  • Pathogens - These are organisms that cause disease all pathogens have antigens on the surface and are identified as foreign by the immune system which then destroy the pathogen
  • Abnormal body cells - Cancerous or pathogen-infected cells have abnormal antigens in their surface which trigger an immune response
  • Toxins - Poisonous molecules, The immune system can respond to toxins, as well as the pathogens that release them.
• How do antigens allow an immune response to identify cells from other individuals of the same species?

  • When receiving cells from another person, those cells have antigens that are different to your own
  • The foreign antigens trigger an immune response
  • This leads to the rejection of transplanted organs if drugs aren't taken