Anti-streptolysin O: Difference between revisions
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When the body is infected with streptococci, it produces [[antibodies]] against the various antigens that the streptococci produce. ASO is one such antibody. So, a raised or rising levels can indicate past or present infection. Historically was one of the first bacterial markers used for diagnosis and follow up of [[rheumatism]] or [[scarlet fever]]. Its importance in this regard has not diminished. |
When the body is infected with streptococci, it produces [[antibodies]] against the various antigens that the streptococci produce. ASO is one such antibody. So, a raised or rising levels can indicate past or present infection. Historically was one of the first bacterial markers used for diagnosis and follow up of [[rheumatism]] or [[scarlet fever]]. Its importance in this regard has not diminished. |
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<pediatric nephrology RN SRIVASTAVA, ARVIND BAGGA.></ref>== Values == |
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== Values == |
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Since these antibodies are produced as a delayed [[hypersensitive]] reaction to the above mentioned bacteria, there is no normal value. Any presence of these antibodies indicates an exposure to these bacteria. However, as many people are exposed to these bacteria and remain asymptomatic, the mere presence of ASO does not indicate disease. |
Since these antibodies are produced as a delayed [[hypersensitive]] reaction to the above mentioned bacteria, there is no normal value. Any presence of these antibodies indicates an exposure to these bacteria. However, as many people are exposed to these bacteria and remain asymptomatic, the mere presence of ASO does not indicate disease. |
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*Children: less than 300 units |
*Children: less than 300 units |
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This titre (value) has a significance only if it is greatly raised, or if a rise in titre can be demonstrated in paired blood samples taken days apart. |
This titre (value) has a significance only if it is greatly raised, or if a rise in titre can be demonstrated in paired blood samples taken days apart.The antibody levels begin to rise after 1 to 3 weeks of strep infection,peaks in 3 to 5 weeks and falls back to insignificant levels in 6 months. |
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Values need to be correlated with a clinical diagnosis. |
Values need to be correlated with a clinical diagnosis. |
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Revision as of 16:25, 20 March 2010
Anti-streptolysin O (ASO or ASLO) is the antibody produced against an antigen produced by Lancefield group A streptococci. The enzyme is called streptolysin O, wherein the O stands for oxygen-labile; the other antigen being oxygen stable streptolysin-S. Both the enzymes are involved in producing hemolysis, i.e., digestion of blood, in particular, beta-hemolysis.
Significance
When the body is infected with streptococci, it produces antibodies against the various antigens that the streptococci produce. ASO is one such antibody. So, a raised or rising levels can indicate past or present infection. Historically was one of the first bacterial markers used for diagnosis and follow up of rheumatism or scarlet fever. Its importance in this regard has not diminished.
<pediatric nephrology RN SRIVASTAVA, ARVIND BAGGA.></ref>== Values == Since these antibodies are produced as a delayed hypersensitive reaction to the above mentioned bacteria, there is no normal value. Any presence of these antibodies indicates an exposure to these bacteria. However, as many people are exposed to these bacteria and remain asymptomatic, the mere presence of ASO does not indicate disease.
Acceptable values, where there is no clinical feature of rheumatism are as follows:
- Adults: less than 200 units
- Children: less than 300 units
This titre (value) has a significance only if it is greatly raised, or if a rise in titre can be demonstrated in paired blood samples taken days apart.The antibody levels begin to rise after 1 to 3 weeks of strep infection,peaks in 3 to 5 weeks and falls back to insignificant levels in 6 months.
Values need to be correlated with a clinical diagnosis.
Estimation
Template:Details3 It is done by serological methods like latex agglutination or slide agglutination. ELISA may be performed to detect the exact titre value.
To detect the titre value, by a non-ELISA method, one has to perform the above agglutination using a serial dilution technique.
Mechanism of action
Template:Details3 These antibodies produced against the bacteria cross react with human antigens (mainly collagen) and hence attack the cellular matrix of various organs, mainly the heart, joints, skin, brain, etc.