MED2042 - Antibodies as diagnostic tools

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MED2042 - Antibodies as diagnostic tools
2010-07-20 17:38:38

Professor J. W. Goding
Show Answers:

  1. What is the definition of antigen?
    Any substance that can provoke an immune response, including the formation of antibodies.
  2. How are antibodies useful in diagnosis?
    • 1. Diagnosis of infection
    • 2. Blood-typing and cross-matching
    • 3. To overcome ambiguities in histopathology where morpholgy alone is insufficient to make a diagnosis (eg, using the CD system)
    • 4. Diagnosis of autoimmune disease
  3. What is the evidence that antibodies bind to antigen?
    • 1. Antibodies neutralise toxins
    • 2. Antibodies precipitate soluble antigens
    • 3. Antibodies can agglutinate bacteria and red cells
  4. How can we detect and measure antibodies?
    Agglutination of particulate antigens (eg, RBCs, bacteria, antigen-coated beads)
  5. What are the problems with Prostate-Specific Antigen (PSA)?
    • 1. Poor sensitivity (eg, low PSA does not mean no cancer)
    • 2. Poor specificity (eg, high PSA does not mean cancer)
  6. What are the danger signs associated with PSA levels?
    • 1. High PSA in younger men
    • 2. High "PSA velocity" (PSA levels rise by more than 2% per year)
  7. If high levels of PSA are present, what clinical procedures should occur next?
    • 1.Ultrasound guided biopsy
    • - If cancer is present...
    • 2. Consider surgery or radiotherapy
    • 3. Measure PSA after treatment
    • - If PSA = 0, recurrence is unlikely
    • - If PSA remains high/continues to rise, excision is incomplete or metastases are present
  8. What hormone is excreted in the urine during pregnancy?
    Human Chorionic Gonadotrophin (HCG)
  9. How can we detect and measure antibodies?
    By attaching a chemical label.