Antigens (Cambridge (CIE) AS Biology): Revision Note

Antigens, self & non-self

• Every cell in the human body has markers on its surface that identify it

• Microorganisms, such as bacteria and viruses, also have their own unique markers

• These markers are called antigens and they allow cell-to-cell recognition

• Antigens are found on cell surface membranes, bacterial cell walls, or the surface of viruses

  • Some glycolipids and glycoproteins on the outer surface of cell surface membranes act as antigens

• Antigens can be either self antigens or non-self antigens:

  • Antigens produced by an organism's own body cells are self antigens

    • Self antigens do not stimulate an immune response

  • Antigens not produced by an organism’s own body cells, e.g. the antigens found on pathogenic bacteria and viruses, are non-self antigens

    • Non-self antigens stimulate an immune response