Immunoprecipitation

Aka: Immunoprecipitation, Immunologic Precipitation, Immunodiffusion Measurement, Immunoelectrophoresis, Ouchterlony Qualitative Immunodiffusion, Radial Immunodiffusion, Immunonephelometry, Immunoturbidimetry

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II. Indications

  1. Detect serum Antigen or Antibody

III. Definitions

  1. Precipitan
    1. Antibody (IgG or IgM) that precipitates in the presence of Antigen
  2. Immunoelectrophoresis
    1. Protein electrophoresis followed by precipitation by double immunodiffusion

IV. Mechanism

  1. Electrophoresis may be used in advance of precipitation (Immunoelectrophoresis)
    1. See Serum Protein Electrophoresis (SPEP)
    2. Separates Proteins via gel electrophoresis
    3. Proteins are then selectively used in precipitation testing
  2. Precipitates specific Antigen or Antibody (precipitan) with its corresponding Antibody or Antigen
  3. Performed in test tube (e.g. cellulose acetate) or on agarose or agar diffusion plate
    1. Antibody-Antigen Precipitant becomes measurable within medium
    2. Agar Gel Immunodiffusion
      1. Double immunodiffusion (e.g. Ouchterlony Qualitative Immunodiffusion)
        1. Qualitative or quantitative measurement of Antigen-Antibody precipitant
      2. Radial Immunodiffusion (e.g. Mancini method)
        1. Antigen-Antibody complex forms a precipitin ring
        2. Antigen concentration quantified by measuring precipitation ring diameter
      3. Electroimmunodiffusion
    3. Test Tube Precipitant in Solution (Quantified by spectrophotometer techniques)
      1. Immunoturbidimetry (absorption of light by precipitant is measured)
      2. Immunonephelometry (reflection of light by precipitant is measured)

V. Disadvantages

  1. Lower Test Sensitivity compared with Agglutination Tests

VI. Resources

  1. Immunoprecipitation (Wikipedia)
    1. https://en.wikipedia.org/wiki/Immunoprecipitation

VII. References

  1. Deshmukh (2019) Eur J Pharm Med Res 7(2):214-16
    1. https://www.researchgate.net/publication/342475322_PRECIPITATION_REACTIONS_IN_IMMUNOLOGY

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