wk 15-immunology

• Clinical immunology


  The study of diseases caused by disorders of the immune system
• Biomedical Science disciplines that immunology crosses


  • Haematology
  • Histopathology
  • Microbiology
  • Biochemistry
• Specialising in Immunology


  • Allows for multidisciplinary career
  • All Biomedical Scientists need to understand the principles of clinical immunology
• Components of the immune system

  • Innate Immunity
  • Adaptive Immunity
• Innate Immunity


  • Physical barriers
  • Phagocytosis
• Adaptive Immunity


  • Specialised cells with memory
  • Specialised into Cellular and Humoral mediated responses
• Cells of the immune system

  • T-cells
  • B-cells
  • CD4+ T-cells
  • CD8+ T-cells
  • Leukocytes
• Antibodies


  Immunoglobulins that specifically bind to antigens
• Antibody structure (IgG)


  • Four polypeptide chains (2 x Heavy (H) and 2 x Light (L))
  • Antigen Binding Sites (110-130 amino acids at tips)
  • Variable regions (VH or VL)
  • Constant domains (Don't vary in sequence, give instruction to immune cells)
• Commonly used antibodies


  • IgM
  • IgG
• What is tested in clinical immunology

  • Infection / Molecular diagnostics
  • Allergies and Hypersensitivity
  • Autoimmune diseases
  • Primary immunodeficiency
• What is tested in clinical virology

  • Infection / Molecular diagnostics
  • Hepatitis
  • CMV
  • HIV
  • Rubella
  • Ebola
  • Covid-19
• HIV


  • Member of the lentivirus family (retrovirus)
  • Infects mature CD4+ T-cells
  • Binds to the CCR5 and CD4 receptor
  • CD4+ T-cells destroyed - leading to AIDS
  • Immune system compromised - B-cells, CD8+ T-cells, macrophages affected
• Clinical features of HIV

  • Blood transmission - IV drug use
  • Sexual transmission
  • 10% will develop acute illness
  • Asymptomatic for 2-15 years
  • Leads to recurrent infections; herpes, bacterial and fungal infections
  • Fever, headache, sore throat, malaise, rash, weight loss, appetite affected
• HIV antibody measurement


  1. Antibodies appear 2-8 weeks post infection

  2. Antibodies directed to Core antigen (p24) and gp41 proteins

  3. p24 antigen is only present for a short period of time in blood

  4. ELISA can be used to detect HIV infection

  5. Antibodies to HIV p24 and HIV protein gp41 are coated to the plate

  6. Patient sera is added

  7. A positive result will be confirmed using SDS-PAGE/ Western Blotting

  8. Chemiluminescence
• Ebola Virus Disease


  • Dangerous infection causing haemorrhaging
  • High mortality rate 50-90%
  • Spreads via blood and bodily secretions
  • Tests need to be performed quickly and safely
• First Antigen Rapid Test for Ebola

  1. ReEBOV Antigen Rapid Test Kit (Corgenix, USA)

  2. Identifies the EBOV VP40 antigen in blood

  3. Dipstick is coated in anti-VP40 antibodies conjugated to gold nanoparticles

  4. Positive reaction forms a complex that forms a pink line on the dipstick

  5. Results in 15 minutes with 92% accuracy
• Consequences of Ebola infection

  • Immune cells reduced from 4-10,000 cells/µl to <1000 cells/µl (Leucopenia)
  • T-cells reduced from 1500-3400 cells/µl (Lymphopenia)
  • Neutrophils reduced from 700 cells/µl (Neutrophilia)
  • Platelets reduced from 130,000-400,000 cells/µl to 50,000-100,000 cells/µl (Thrombocytopenia)
  • Hepatocyte destruction = Elevated aspartate aminotransferase
  • Immune response can generate a cytokine storm
  • Survival linked with strong IgM and IgG activating strong CD8+ cell response
• Immunological techniques


  • Immunochemistry (IHC/ICC)
  • Immunofluorescence
  • Antibodies in medicine
  • ELISA
  • ELISPOT
  • Immunoassays
  • Immunodiffusion
  • Agglutination
  • Flow Cytometry and FACS
• Antigen


  Any substance capable of eliciting an immune response, usually a CHO, protein or lipid, displaying regions of AAs called 'antigenic determinant groups' or 'epitopes' to which antibodies specifically bind
• Clinical immunology


  The study of diseases caused by disorders of the immune system
• Antibody-antigen binding


  Antigens commonly have several different epitopes, different antibodies will bind to the same antigen, each type binds only to its specific epitope
• Biomedical Science disciplines that immunology crosses


  • Haematology
  • Histopathology
  • Microbiology
  • Biochemistry
• IgG


  Comprises 2 pairs of polypeptide chains (1 pair 'heavy', 1 pair 'light') linked by disulphide bonds, all 4 chains have variable domains at their terminal ends that bind only to their specific antigenic epitope
• Specialising in Immunology


  • Allows for multidisciplinary career
  • All Biomedical Scientists need to understand the principles of clinical immunology
• Components of the immune system

  • Innate Immunity
  • Adaptive Immunity
• Innate Immunity


  • Physical barriers
  • Phagocytosis
• Adaptive Immunity


  • Specialised cells with memory
  • Specialised into Cellular and Humoral mediated responses
• Polyclonal antibodies


  Produced by a humoral response in animals by immunisation with the antigen of interest, result in clones of differing specificity (bind to different epitopes of the same antigen)
• Cells of the immune system

  • T-cells
  • B-cells
  • CD4+ T-cells
  • CD8+ T-cells
  • Leukocytes
• Antibodies


  Immunoglobulins that specifically bind to antigens
• Antibody structure (IgG)


  • Four polypeptide chains (2 x Heavy (H) and 2 x Light (L))
  • Antigen Binding Sites (110-130 amino acids at tips)
  • Variable regions (VH or VL)
  • Constant domains (Don't vary in sequence, give instruction to immune cells)
• Commonly used antibodies


  • IgM
  • IgG
• Monoclonal antibodies


  Produced from a single clone from hybridomas of plasma cell and neoplastic myeloma cells, result in specific clones (each clone binds to the same epitope)
• What is tested in clinical immunology

  • Infection / Molecular diagnostics
  • Allergies and Hypersensitivity
  • Autoimmune diseases
  • Primary immunodeficiency
• What is tested in clinical virology

  • Infection / Molecular diagnostics
  • Hepatitis
  • CMV
  • HIV
  • Rubella
  • Ebola
  • Covid-19
• ELISA


  One of the most commonly used assays, used in Immunology and Virology, usually manual (can be automated), unknown Ags attached to solid phase in a multiwell plate, enzyme-linked Abs applied, chromogenic substrate added, coloured end product indicates Ag-Ab binding, intensity directly proportional to quantity of bound Ag (spectrophotometer), reference range (known Ab conc); standard curve
• HIV


  • Member of the lentivirus family - retrovirus
  • Infects mature CD4+ T-cells
  • Binds to the CCR5 and CD4 receptor
  • CD4+ T-cells destroyed - leading to AIDS
  • Immune system compromised - B-cells, CD8+ T-cells, macrophages affected
• Clinical features of HIV

  • Blood transmission - IV drug use
  • Sexual transmission
  • 10% will develop acute illness
  • Asymptomatic for 2-15 years
  • Leads to recurrent infections; herpes, bacterial and fungal infections
  • Fever, headache, sore throat, malaise, rash, weight loss, appetite affected
• Types of ELISA


  • DIRECT
  • INDIRECT
  • SANDWICH