lymphocytes

• what are the two different types of lymphocytes

  b (bone marrow)

  t (thymus)
• what is the role of t-helper cells

  CD4 receptors on the cell surface membrane bind to the antigens on the MHC

  releases interleukins which stimulates t-cells to differentiate, macrophages to enhance phagocytosis effect, b-cells to make antibodies
• what is the role of t-killer cells

  releases perforin and hydrogen peroxide
• what is the role of t-regulator cells

  suppresses immune system (kills all lymphocytes bar memory cells) preventing auto immune diseases
• what is the role of t-memory cells

  support immunological memory leading to a rapid secondary response
• what is the role of b-plasma cells

  short lived

  produces antibodies
• what is the role of b-effector cells

  they are the inactive version of b-plasma
• what is the role of b-memory cells

  immunological memory of antigen
• what is the humoral response

  clonal selection and clonal expansion
• what is clonal selection

  b-lymphocytes with the correct cell surface antigen are able to recognise pathogen
• what happens in clonal expansion

  specific b-lymphocytes divide rapidly by mitosis