ANTISTREPTOLYSIN O- ASO TITRE TEST

1) 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.
2) When the body is infected with streptococci, it produces antibodies against the various antigens that the streptococci produce. ASO is one such antibody. So, raised or rising levels can indicate past or present infection.
3) Historically was one of the first bacterial markers used for diagnosis and follow up of rheumatism or scarlet fever.
4) Since these antibodies are produced as a delayed hypersensitive reaction to the above mentioned bacteria, there is no normal value.
5) 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.
6) Acceptable values, where there is no clinical feature of rheumatism are as follows: Adults: less than 200 units, Children: less than 300 units.