Radioimmunoassay - Revision history

Bara: /* Applications */

2012-03-17T16:53:05Z

Applications

Bara at 16:52, 17 March 2012

2012-03-17T16:52:40Z

Bara at 14:52, 12 August 2010

2010-08-12T14:52:00Z

Bara at 14:51, 12 August 2010

2010-08-12T14:51:45Z

A.allison: Text replace - 'IgG' to 'IgG'

2010-06-12T16:32:10Z

Text replace - 'IgG' to 'IgG'

A.allison: Text replace - 'Immunology - WikiBlood' to 'Immunology'

2010-06-12T16:09:52Z

Text replace - 'Immunology - WikiBlood' to 'Immunology'

Kwhittle: /* Technique */

2009-08-14T13:05:14Z

Technique

Kwhittle: /* Principle */

2009-08-14T13:03:35Z

Principle

Kwhittle: /* Introduction */

2009-08-14T12:49:15Z

Introduction

Jtulloch at 08:43, 19 September 2008

2008-09-19T08:43:30Z

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 **RIA used in this way has been employed in the detection of the hepatitis B surface antigen in donor blood, reducing the occurrence of hepatitis infections as a result of blood transfusions in humans
 *Measuring plasma levels of hormones and controlled substances
-*Measuring anti-DNA antibodies present in systemic lupus erythematosus (SLE)
+*Measuring anti-DNA antibodies present in [[SLE|systemic lupus erythematosus (SLE)]]
 ==Drawbacks==

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 ==Introduction==
 The radioimmunoassay (RIA) is a sensitive technique used to detect the presence of antigen in a sample using radiolabelled antibodies. Developed in the 1960's, the RIA proved a powerful tool in antigen detection, although the procedure was soon overtaken by ELISA, which utilises enzymes rather than radioactive labels. RIAs are still used today however, to measure:
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 [[Category:Immunological Testing]]

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 *Measuring anti-DNA antibodies present in systemic lupus erythematosus (SLE)
-=Drawbacks=
+==Drawbacks==
 Although the RIA is a very sensitive test, and therefore widely-used, there are disadvantages to its use:
 *The substances being used are radioactive

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 {{review}}
 ==Introduction==
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 *Iodine is naturally concentrated in the thyroid gland, whether radioactive or not, and incorporated into thyroxine
 Consequently, ELISA has largely overtaken RIA as a preferred diagnostic tool

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 *There are various methods to separate the antigen-antibody complexes from the free antigen:
 **Precipitate complexes using secondary isotype-specific anti-immunoglobulin
-**If complex contains IgG, it can be removed by mixing with formalin-killed ''Staphylococcus aureus''- protein A of ''S. aureus'' has a high affinity for IgG
+**If complex contains [[IgG]], it can be removed by mixing with formalin-killed ''Staphylococcus aureus''- protein A of ''S. aureus'' has a high affinity for [[IgG]]
 *** Removal of the complex by either of these methods leaves an amount of free labeled antigen in the supernatant (liquid section from precipitation)- the radioactivity of this can be measured and the value taken away from the total amount of labeled antigen added (known amount)= amount of bound labeled antigen
 **A number of solid-phase RIAs have been developed

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 {{toplink
 |backcolour = FFE4E1
-|linkpage =Immunology - WikiBlood
+|linkpage =Immunology
 |linktext =IMMUNOLOGY
 |sublink1 =Immunological testing - WikiBlood

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 ==Technique==
-*The antigen is often labelled with a gamma-emitting isotope, e.g. iodine-125
+*The antigen is often labeled with a gamma-emitting isotope, e.g. iodine-125
-**Beta-emtting isotopes such as tritium are also often used
+**Beta-emitting isotopes such as tritium are also often used
-# Determine the amount of antibody required to bind ~50% of radiolabelled antigen in mixture- ''required to ensure the number of epitopes presented by labelled antigen exceeds number of antibody binding sites''
+# Determine the amount of antibody required to bind ~50% of radiolabeled antigen in mixture- ''required to ensure the number of epitopes presented by labeled antigen exceeds number of antibody binding sites''
-# Add unlabelled antigen to mixture
+# Add unlabeled antigen to mixture
 # Separate antigen-antibody complex from free antigen by precipitation
 # Measure radioactivity in precipitate
 *There are various methods to separate the antigen-antibody complexes from the free antigen:
-**Precipitate complexes using secondary isotype-specific antiimmunoglobulin
+**Precipitate complexes using secondary isotype-specific anti-immunoglobulin
 **If complex contains IgG, it can be removed by mixing with formalin-killed ''Staphylococcus aureus''- protein A of ''S. aureus'' has a high affinity for IgG
-*** Removal of the complex by either of these methods leaves an amount of free labelled antigen in the supernatant (liquid section from precipitation)- the radioactivity of this can be measured and the value taken away from the total amount of labelled antigen added (known amount)= amount of bound labelled antigen
+*** Removal of the complex by either of these methods leaves an amount of free labeled antigen in the supernatant (liquid section from precipitation)- the radioactivity of this can be measured and the value taken away from the total amount of labeled antigen added (known amount)= amount of bound labeled antigen
 **A number of solid-phase RIAs have been developed
-***Sometimes the antibody can be absorbed onto the surface- the amount of radiolabelled antigen bound to the beads can be measured after washing
+***Sometimes the antibody can be absorbed onto the surface- the amount of radiolabeled antigen bound to the beads can be measured after washing
 ***Antibody can be immobilised on PVC or polystyrene

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 ==Principle==
-*The general priniciple behind the RIA is the competitive binding of a radiolabelled antigen and unlabelled antigen to a high-affinity antibody.
+*The general priniciple behind the RIA is the competitive binding of a radiolabeled antigen and unlabeled antigen to a high-affinity antibody.
-*Labelled antigen is mixed with antibody until binding sites are saturated
+*Labeled antigen is mixed with antibody until binding sites are saturated
-*Samples of unlabelled antigen (unknown concentration) are added in progressively increasing amounts
+*Samples of unlabeled antigen (unknown concentration) are added in progressively increasing amounts
 **The two different antigens compete for the binding sites on the antibody
-**As the concentration of unlabelled antibody increases, more labelled antigen will be displaced
+**As the concentration of unlabeled antibody increases, more labeled antigen will be displaced
-*The decrease in bound-radiolabelled antigen is measured- an indication of the amount of antigen present in sample
+*The decrease in bound-radiolabeled antigen is measured - an indication of the amount of antigen present in sample
 ==Technique==

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 ==Introduction==
-The radioimmunoassay (RIA) is a sensitive technique used to detect the presence of antigen in a sample using radiolabelled antibodies. Developed in the 1960's, the RIA proved a powerful tool in antigen detection, although the procedure was soon overtaken by ELISA, which utilise enzymes rather than radioactive labels. RIAs are still used today however, to measure:
+The radioimmunoassay (RIA) is a sensitive technique used to detect the presence of antigen in a sample using radiolabelled antibodies. Developed in the 1960's, the RIA proved a powerful tool in antigen detection, although the procedure was soon overtaken by ELISA, which utilises enzymes rather than radioactive labels. RIAs are still used today however, to measure:
 *Hormone levels in blood and tissue fluids
 *Serum proteins

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