Immunity and antigens

• How does the immune system recognize healthy cells?

  By identifying unique molecules on cell surfaces
• What are foreign substances that the immune system identifies?

  Pathogens
• What type of cells can identify non-self cells?

  Lymphocytes
• What role do unique molecules on cell surfaces play?

  They act as markers for cell identification
• What are the identifying molecules on cells called?

  Antigens
• What do lymphocytes recognize on the surface of cells?

  Unique shapes of antigens
• What types of cells can lymphocytes identify?

  Pathogens, abnormal cells, and toxins
• How many different types of lymphocytes are in the body?

  Approximately 10 million
• What happens to lymphocytes that are complementary to self cells?

  They die or have their production suppressed
• Where do lymphocytes mature after being exposed to non-self cells?

  In the thymus or bone marrow
• What can happen if the lymphocyte process fails?

  It can lead to autoimmune diseases
• What are antigens typically made of?

  Proteins
• What is antigen variability?

  Frequent mutations in pathogen DNA
• Why do we need a new flu vaccine every year?

  Due to frequent mutations of the virus
• What happens to memory cells when antigens change shape?

  They can no longer recognize the new shape
• What is the consequence of new antigen shapes on immunity?

  Previous immunity becomes ineffective
• What should happen to lymphocytes that may harm self cells?

  They should be destroyed before maturing
• What are the key points about antigens and the immune system?

  • Antigens are typically proteins on cell surfaces
  • They generate immune responses by lymphocytes
  • They help differentiate self cells from pathogens
  • Pathogen DNA mutates regularly, causing antigen variability
  • New shapes of antigens can render previous immunity ineffective
• What are the four types of non-self cells recognized by lymphocytes?

  1. Pathogens (bacteria, viruses, fungi)
  2. Cells from organ transplants
  3. Abnormal body cells (e.g., cancer cells)
  4. Toxins released by pathogens (e.g., cholera)
• What is the process of lymphocyte development in relation to self cells?

  • Lymphocytes are produced during fetal development
  • Lymphocytes complementary to self cells are destroyed
  • Remaining lymphocytes recognize pathogenic or non-self cells
  • This process continues after birth in the bone marrow