• T cells, sometimes known as T lymphocytes, are a?type of white blood cell?involved with the specific immune response
  • They are produced in the bone marrow and finish maturing in the?thymus, which is where the?T?in their name comes from
• Mature?T cells?have specific cell surface receptors called?T cell receptors
• These receptors have a?similar structure to antibodies?and are each?specific to a particular type of antigen

?Mature T cells have many different types of receptor on the cell surface membrane; these receptors will bind to different antigens on antigen presenting cells

• T cells are?activated?when they encounter and?bind to their specific antigen?on the surface of an antigen presenting cell
  • This?antigen-presenting?cell might be a?macrophage,?an?infected body cell, or the?pathogen?itself
• These activated T cells?divide?by?mitosis?to increase in number
  • Dividing by mitosis produces?genetically identical cells, or?clones, so all of the daughter cells will have the?same type of T cell receptor on their surface
• As they divide by mitosis the T cells?differentiate?into?three main types?of T cell
  • T helper cells
    • Release chemical signalling molecules that help to?activate B cells
  • T killer cells
    • Bind to and?destroy infected cells?displaying the relevant specific antigen
  • T memory cells
    • Remain in the blood?and enable a faster specific immune response if the same pathogen is encountered again in the future