IMMUNITY and ANTIGENS

• How does the immune system recognize healthy cells?

  By identifying unique surface molecules
• What are foreign substances that the immune system identifies?

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

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

  Antigens
• What role do antigens play in the immune response?

  They trigger the immune response
• What types of pathogens can lymphocytes identify?

  Bacteria, fungi, viruses
• How do lymphocytes respond to organ transplants?

  They detect foreign cells as harmful
• What happens to abnormal body cells like cancer cells?

  Lymphocytes detect their different antigens
• What do some pathogens release into the blood?

  Toxins
• How many different types of lymphocytes are in the body?

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

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

  Thymus or bone marrow
• What can result from lymphocytes attacking self cells?

  Autoimmune diseases
• What are antigens typically made of?

  Proteins
• What is antigen variability?

  Frequent mutations in pathogen DNA
• Why do new flu vaccines need to be created annually?

  Pathogens mutate and change antigen shapes
• What happens to memory cells when a pathogen mutates?

  They can no longer recognize the new antigen
• What is the role of lymphocytes in the immune system?

  To recognize and respond to antigens
• What are the key points about antigens and the immune system?

  • Antigens are specific molecules on cell surfaces.
  • They are typically proteins that generate immune responses.
  • The immune system differentiates between self and non-self cells.
  • Pathogens can mutate, leading to antigen variability.
  • Memory cells may fail to recognize mutated antigens.
• What is the process of lymphocyte development and maturation?

  1. Lymphocytes are produced during fetal development.
  2. Lymphocytes complementary to self cells are destroyed.
  3. Remaining lymphocytes recognize non-self cells.
  4. Lymphocytes mature in the thymus or bone marrow.
  5. Autoimmune diseases can occur if self cells are attacked.
• What are the implications of antigen variability for vaccination?

  • Frequent mutations in pathogens change antigens.
  • Previous immunity may become ineffective.
  • New vaccines are required to match current antigens.
  • This is particularly relevant for the flu virus.