Lysis of erythrocytes by a hemolysin produced by a group B Streptococcus sp.

Abstract

An improved procedure for the isolation and purification of the hemolysin produced by a group B streptococcus was developed, and the inactivation of partially purified hemolysin by several enzymes was studied. Hemolysin obtained in buffer containing starch and Tween 80 was inactivated by subtilisin and alphaamylase, suggesting that the hemolysin may consist of a protein hemolytic moiety complexed to starch which acts as a carrier or stabilizer. Properties of the hemolytic reaction were studied by using sheep erythrocytes as target cells. Experiments to examine the kinetics of hemolysis at different hemolysin concentrations resulted in a family of sigmoidal curves characterized by a short prelytic lag phase followed by a period of rapid release of hemoglobin. The binding of the group B hemolysin at 37°C was rapid; within 3 min, most of the cells had bound sufficient hemolysin to produce lysis. In contrast, the hemolysin did not bind to erythrocytes at 0°C. The length of the prelytic lag period and the rate of hemolysis were also temperature dependent. A decrease in total hemolysis was observed when the target cell/hemolysin ratio was increased, suggesting that a multihit response is required for lysis. Intracellular 86Rb and hemoglobin were released at the same rate from hemolysin-treated cells, indicating that a colloid-osmotic process is not involved in the lytic mechanism.