cellular immune response

• T lymphocytes

  Also called T cells, involved in the specific immune response
• T cells

  • Made in the bone marrow
  • Mature in the thymus
• Cell-mediated response

  The response involving T cells
• Specific immune response

  Response to an exact antigen or cell surface molecule
• Antigen presenting cells (APCs)

  Any cell that presents a non-self antigen on their cell surface membrane
• Types of APCs

  • Infected body cells with viral antigens
  • Phagocytes like macrophages after engulfing pathogens
  • Cells of a transplanted organ
  • Abnormal cells like cancer cells
• APCs trigger the B cell mediated response
• Cell-mediated response

  1. Pathogen engulfed by phagocytosis

  2. Antigens presented on APC surface

  3. Helper T cells bind to antigens on APC

  4. Helper T cells activate and replicate

  5. Helper T cells stimulate B cells, macrophages, and become memory or cytotoxic T cells
• Cytotoxic T cells

  Also called killer T cells, can destroy abnormal or infected cells
• How cytotoxic T cells kill infected cells

  1. Release perforin protein

  2. Perforin embeds into cell membrane, creating pores

  3. Cell contents can enter/leave, causing cell death
• Cytotoxic T cells kill infected cells to prevent virus replication and spread
• Sore throat from a cold is caused by cytotoxic T cells destroying infected cells in the throat
• T lymphocytes

  Cells involved in cell-mediated immunity
• T lymphocytes are produced in the bone marrow and migrate to the thymus gland to mature
• T Cell receptor

  Attaches to antigens on the surface of cells
• Each unique T lymphocyte has a unique T Cell receptor
• Situations where T lymphocytes can recognize antigens

  • Cell infected with a virus
  • Cell is a mutated cancer cell
  • Transplanted cell or tissue
  • Macrophage engulfs a pathogen
• Antigen presenting cells

  • Cells that display antigens on their surface for T lymphocytes to recognize
• T helper cells

  T lymphocytes that carry out a range of functions
• T helper cell activation

  1. Attaches to antigen on antigen presenting cell

  2. Undergoes mitosis to produce clones

  3. Produces cytokines (interleukins)

  4. Can activate cytotoxic T cells
• Cytotoxic T cells (T killer cells)

  Identify and destroy abnormal or infected cells
• T memory cells

  Long-lived T cells that can rapidly differentiate into cytotoxic T cells if the same pathogen is encountered again
• T regulator cells

  Down-regulate the immune system once a pathogen has been destroyed, and help prevent autoimmune disorders