Cell mediated immune system

• What type of response is phagocytosis?

  A non-specific response
• What type of immune response involves T cells and B cells?

  A specific immune response
• What type of white blood cells are involved in the cell-mediated response?

  T-lymphocytes
• What do T-lymphocytes target?

  Pathogens inside and outside cells
• What can T-helper cell receptors bind to?

  Antigens on body cells/APCs
• What happens to phagocytes after they engulf a virus?

  They present some of the pathogen's antigens on their membrane
• What are antigen-presenting cells (APCs)?

  Phagocytes or infected cells that display pathogen antigens on their surface
• Where are T lymphocytes made?

  Thymus gland
• What is the role of T helper cells in the immune response?

  They bind to foreign antigens on APCs
• How do T helper cells recognise antigen-presenting cells?

  They have receptors that are complementary to the antigens
• What happens when a T helper cell binds to an antigen?

  The T helper cell is activated
• What does the activated T helper cell do after binding?

  It divides by mitosis and differentiates into different T cells
• What are cytotoxic (killer) T cells?

  T cells that destroy infected or foreign cells
• What is the role of T memory cells?

  They allow a faster response to the antigen in the future
• What other cells do activated T helper cells activate?

  They activate B cells and increase phagocyte numbers
• What are the two types of white blood cells that carry out phagocytosis?

  Macrophages and neutrophils
• What is the difference between macrophages and neutrophils?

  Neutrophils often die soon after engulfing the pathogen, whereas macrophages are long lived and help to trigger the specific immune response
• What is the function of APCs and how are they formed?

  • When a macrophage engulfs a pathogen, it displays some of the pathogen's antigens on its surface
  • This signals to the lymphocytes that there are pathogens invading the body
  • Body cells that have been invaded by a virus also present its antigen on their surface
  • This shows the cell has been invaded and needs to be destroyed
• What are T-lymphocytes and what is their function in the specific immune response?

  • T-lymphocytes will respond to the antigen being displayed by an APC
  • Made in the bone marrow, but mature in the thymus gland
  • Each T cell has its own unique set of proteins and glycoprotein molecules on its cell surfacce membrane which act as receptors