Immunodiagnostics and Serology
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Questions and Answers

What is the primary focus of serology in vitro?

  • Identifying cancer biomarkers
  • Detecting antigens in a sample (correct)
  • Studying the immune response in vivo
  • Analyzing hormone levels in serum

    • Which type of serological test detects the presence of antibodies in a sample?

  • Immunoassay test
  • Titration test
  • Indirect test (correct)
  • Direct test

    • What does a positive result in a direct serological test indicate?

  • Exposure to an antigen
  • Immune response to an infection
  • Autoimmune disease
  • Presence of an antigen in the sample (correct)

    • What is the purpose of serial dilutions in serology?

    <p>To determine the concentration of antibodies or antigens</p> Signup and view all the answers

    Why is it important to understand antibody production dynamics in serology?

    <p>All of the above</p> Signup and view all the answers

    What is the term for the concentration of antibodies or antigens in a sample?

    <p>Titer</p> Signup and view all the answers

    What is the significance of paired serology in diagnosis?

    <p>It helps in distinguishing between acute and convalescent phases of an infection</p> Signup and view all the answers

    Which type of serological test is commonly used to diagnose infectious diseases?

    <p>Both direct and indirect tests</p> Signup and view all the answers

    What is the primary difference between IgG and IgM antibody levels?

    <p>IgG levels are more specific, while IgM levels are more sensitive.</p> Signup and view all the answers

    What is the purpose of a cut-off in antibody levels?

    <p>To separate true positives from false positives.</p> Signup and view all the answers

    Which of the following is true about the antibody levels at 0 days?

    <p>IgG levels are higher than IgM levels.</p> Signup and view all the answers

    What is the advantage of using Cut-off 2?

    <p>It is more specific and detects fewer false positives.</p> Signup and view all the answers

    What is the relationship between the time of infection and the antibody levels?

    <p>The antibody levels increase as the time of infection increases.</p> Signup and view all the answers

    What is the purpose of using multiple cut-offs?

    <p>To determine the best cut-off value.</p> Signup and view all the answers

    What is the purpose of Paired serology?

    <p>To determine the time of infection</p> Signup and view all the answers

    Study Notes

    Immunodiagnostics

    • Study of antigen-antibody interactions in vitro
    • One of the most commonly used diagnostic tools
    • Used for infectious diseases, hormone detection, cancer, and autoimmunity
    • Basis of several different techniques
    • Most commonly performed on serum (blood) samples

    Serology

    • Direct: detects the presence of the antigen in the sample, a positive result means infection
    • Indirect: detects the presence of antibodies or other products of the immune response in the sample, a positive result means exposure

    Titers

    • Expresses the concentration of antibodies/antigens
    • Correlates with the highest dilution at which antibodies/antigens are still detectable

    Understanding Antibody Production

    • Important for correct diagnosis
    • Choice of target antibody
    • Time of testing
    • Paired serology

    Antibody Levels

    • IgM: early production, correlates with acute infection
    • IgG: later production, correlates with chronic infection
    • Cut-off values: sensitivity vs specificity
    • Paired serology: 1st test (acute phase) and 2nd test (convalescent phase)

    Immunodiagnostic Techniques

    • Enzyme-Linked Immunosorbent Assay (ELISA)
      • Uses enzyme-labeled antibodies or antigens to detect and/or measure analyte concentrations
      • Variations: Direct ELISA, Indirect ELISA, Sandwich ELISA
    • Lateral or Bidirectional Flow Assays
      • Qualitative or semi-quantitative
      • Point-of-care testing
      • Fast results
      • No lab needed
    • Immunofluorescence
      • Fluorescent-labeled antibodies
      • Used on tissue or cells, on microscope slides
      • Requires a fluorescent microscope to read results
    • Immunohistochemistry
      • Used on frozen or formalin-fixed tissues
      • In situ results
      • Detects tissue proteins or pathogen antigens
    • Agglutination
      • Reaction between antibody + particulate antigen or antibody + soluble antigen coated latex beads
    • Immunoprecipitation assays
      • Precipitation of antigen-antibody complexes
      • Exploits concentrations of antibody and antigen to measure relative quantities (titers)
      • Solution-based and gel-based techniques

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    Related Documents

    PID+Immunodiagnostics Fall 23 PDF

    Description

    Immunodiagnostics is the study of antigen-antibody interactions in vitro, used for diagnosing infectious diseases, hormone detection, cancer, and autoimmunity. Serology is a branch of immunodiagnostics that detects the presence of antigens or antibodies in a sample.

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