• 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
  • cytotoxic (killer) 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

   

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