Marker of the presence of streptococcal infection in the body
Antistreptolysin-O (ASL-O) is an antibody to streptolysin produced by beta-hemolytic group A streptococcus. It is a marker of the body's sensitization to streptococcal antigens. A persistent and prolonged increase in the level of anti-streptolysin-O after a sore throat may be a harbinger of a rheumatic process.