cellular response

• T cell responses are cell mediated as they only respond to antigens presented on cells not antigens floating in body fluids, like blood
• Antigen Presenting Cells (APC)


  • Any cell that presents non-self antigen on surface, this could be infected body cells that present viral antigens on surface
  • Transplanted organ cells with different shaped antigens to self-cell antigens
  • Cancer cells with abnormal shaped self-cell antigens
• T cell activation


  1. After pathogen destroyed by phagocyte (phagocytosis), helper T cells have receptors that can attach to antigens now presented on phagocyte (APC)

  2. Once attached, T cells activated to divide by mitosis & replicate to make many clones

  3. Cloned T helper cells differentiate into different cells
• Helper T cells


  • Some remain as helper T cells which activate B cells
  • Some stimulate macrophages to perform more phagocytosis
  • Some become memory cells
  • Some become cytotoxic T cells
• Cytotoxic T cells


  Destroy abnormal/infected cells by releasing protein (perforin) which embeds in cell surface membrane makes pore/hole so cell lyses, causing cell death - this sacrifices body cells to prevent viral replication
• T cells (lymphocyte)


  White blood cells involved in specific immune response (specific to certain antigens)

  • Made in bone marrow, mature in thymus