Final Revision

• Passive immunization

  • Naturally-acquired immunization: transfer of maternal antibodies to new-born infants through breast milk or to the foetus through the placenta Duration: ~6months-1year Memory: no
  • Artificially-acquired immunization: administration of the antibody containing serum fraction (antiserum) from immune individuals Duration: 2-3weeks Memory: no
• Active immunization

  • Naturally-acquired immunization: induced after natural infection of the host Duration: lifelong Memory: yes
  • Artificially-acquired immunization: vaccination i.e. intentional exposure to forms of a pathogen that do not cause disease (a vaccine) Duration: many years Memory: yes
• The common vaccines currently in use consist of:

  • Live attenuated organisms
  • Inactivated or “killed” bacterial cells or viral particles
  • Protein or carbohydrate fragments (subunits) of the target organism
  • Conjugate or component vaccines
• Azathioprine and cyclophosphamide

  Mitotic inhibitors that diminish B- and T-cell proliferation
• Methotrexate


  Inhibits dihydrofolate reductase, an enzyme involved in the synthesis of nucleotides, inhibits the replication and proliferation of rapidly dividing cells, including immune cells
• Generalized immunosuppressive therapy

  • Can dramatically increase survival rates of allografts
  • Used in combination with corticosteroids
• Generalized immunosuppressive therapy

  Affects any rapidly dividing non immune cells (e.g. gut epithelial cells or liver) thus leading to serious or even life-threatening complications
• More specific immune suppression

  • Cyclosporin A (CsA), tacrolimus (FK506) and rapamycin (sirolimus)
  • Block the activation and proliferation of resting T cells by interfering with signaling pathways important for clonal expansion of T cells
• Anti-thymocyte globulin (ATG)


  Can be used to deplete lymphocytes in recipients prior to transplantation
• Muromonab (OKT3, anti-CD3)


  Blocks T cell activation by causing apoptosis of T cells
• Daclizumab, basiliximab (anti-IL2 receptor antibody)

  • Blocks T cell proliferation via blocking the binding of IL-2
  • Mediates opsonization of IL-2R bearing cells
• Belatacept (CTLA-4-Ig)

  A fusion protein that inhibits T cell activation by blocking the binding of costimulatory B7 to CD28
• Alemtuzumab (anti-CD52)

  Depletes pool of T cells by binding to them and causing complement mediated lysis (CD52 is a lymphocyte marker)
• Rituximab (anti - CD20 )

  Depletes mature B cells
• Hyperacute rejections can begin within minutes to 24h of transplantation

  Acute rejections begin in the first few weeks after transplantation

  Accelerated acute rejections occur within days; due to a memory response

  Chronic rejections can occur from months to years after transplantation
• Blood lymphocytes from an individual with X-linked agammaglobulinemia show only binding to antibodies against the T-cell marker CD3

  This indicates an absence of B cells in these patients
• Coombs test

  These tests use the Coombs reagent which contains human anti-immunoglobulin antibodies (anti-IgG antibodies) to detect the antibodies that cause haemolytic disease of the newborn
• Direct Coombs test Designed to identify maternal anti-RhD antibodies that are already bound to infant RBCs
• Indirect Coombs test is designed to identify Rh-negative mothers who are producing anti-Rh antibodies of the IgG isotype, which may be transferred across the placenta harming Rh-positive foetuses
• When CTLA-4 is bound to another protein called B7, it helps keep T cells from killing other cells, including cancer cells.