Effect of streptolysin S on responsiveness of polymorphonuclear leucocytes

Most strains of Streptococcus pyogenes [group A, beta-haemolytic] contain a potent leukotoxic factor. When bacteria containing relatively large quantities of this factor are ingested by or come into contact with Poly Polymorphonuclear Leucocytes [PMNs], the neutrophils are destroyed. Death of PMNs is associated with intracytoplasmic rupture of PMN granules; this release of granule contents is thought to be the leukocidal killing mechanism. Purified, Streptolysins S [SLS], at concentrations of b etween 8000 HU/ml, when added directly to zymosan - induced rabbit PMNs, caused iinhibition of the PMNs chemiluminescence response

Studies on the toxic effects of streptolysin 'O': effect on the contractility of isolated and intact mammalian and amphibian heart.

The effect of streptolysin O (a streptococcal exotoxin) on the myocardial contractility of isolated and intact mammalian and amphibian heart has been investigated. Streptolysin O caused marked reduction or complete cessation of myocardial contractility of mammalian and amphibian heart both in vivo and in vitro. The effect of submaximal doses of streptolysin O on isolated atria was reversible after repeated washings and the myocardial depressant effect of streptolysin O on isolated atria was reversible after repeated washings and the myocardial depressant effect of streptolysin O was not antagonised by atropine. These observations would suggest that streptolysin O is cardiotoxic and may be involved in the causation of myocardial failure associated with acute rheumatic fever in man.