Similarities between complement-mediated and streptolysin S-mediated hemolysis

The oxygen-stable hemolysin streptolysin S (SLS) of Streptococcus pyogenes is encoded in part by the pel/sagA gene product. Antibodies to a synthetic peptide from the C terminus of the Pel/SagA open reading frame inhibited he molysis mediated by both culture supernatants from multiple M serotypes of S. pyogenes isolates or a commercially available SLS preparation. Analysis of the SLS-mediated hemolytic reaction demonstrated that it was temperature - and concentration-dependent. Like complement-mediated hemolysis it confor ms to the prediction of a one-hit mechanism of hemolysis. A number of inter mediates in the SLS-mediated hemolysis of sheep erythrocytes could be disti nguished. SLS could bind to erythrocytes below 17 degreesC; however, lysis could only occur at temperatures > 23 degreesC. Following binding of SLS an d washing, a papain-sensitive intermediate could be distinguished prior to insertion of the SLS complex into the erythrocyte membrane, which resulted in formation of a transmembrane pore and led to irreversible osmotic lysis of the cell. These intermediates were similar to those described previously during complement-mediated hemolysis.