The Role of Helper T cells (AQA A Level Biology)

The Role of Helper T cells

• Activated T-lymphocytes (those that have receptors specific to an antigen) divide by mitosis to increase in number (similar to the clonal selection and clonal expansion of B-lymphocytes)

• These T-lymphocytes differentiate into two main types of T cell:

  • Helper T cells

    • Helper T cells assist other white blood cells in the immune response

    • They release cytokines (hormone-like signals) which stimulate:

      • The maturation of B-lymphocytes into antibody-secreting plasma cells

      • The production of memory B cells

      • The activation of cytotoxic T cells, which destroy virus infected cells and tumour cells

    • An increased rate of phagocytosis

  • T killer cells

    • T killer cells patrol the body in search of antigen-presenting body cells

    • T killer cells attach to the foreign antigens on the cell surface membranes of infected cells and secrete toxic substances that kill the infected body cells, along with the pathogen inside

      • Perforins secreated by T killer cells punch a hole in the cell surface membrane of infected cells,allowing toxins to enter

Helper T cells and killer T cells carry out different functions during an immune response