antigens and antigenic variability

• Antigen


  Molecules, typically proteins, located on the cell surface membrane that generate an immune response
• Lymphocytes


  • Cells that can identify non-self cells
  • Each lymphocyte can recognize one unique antigen shape
• The immune system can identify and respond to four types of non-self cells: pathogens, transplanted cells, abnormal body cells, and toxins
• There are approximately 10 million different types of lymphocytes in the body
• Development of lymphocytes


  1. Lymphocytes complementary to self-cell antigens are destroyed or suppressed during fetal development and after birth

  2. Remaining lymphocytes are complementary to non-self antigens
• Pathogen DNA mutation


  Changes the shape of antigens on the pathogen's surface
• A new flu vaccine is created each year due to frequent mutation of the influenza virus
• Autoimmune diseases are caused by lymphocytes attacking self-cells