Effect of Escherichia coli alpha-Hemolysin on human peripheral leukocyte viability in vitro

Abstract

To gain further evidence that Escherichia coli alpha-hemolysin has a role in pathogenesis, its effect on human peripheral leukocyte viability was studied in vitro. Viability of leukocytes exposed to low doses of alpha-hemolysin decreased nearly 10-fold within 15 min of exposure. This response was dose and time dependent and was neutralized by antiserum, heat, proteases, and lipase. To gain further evidence that alpha-hemolysin was the molecule responsible for leukotoxicity, preparations of alpha-hemolysin were passed through a hydrophobic interaction chromatographic column. Alpha-hemolysin prepared in this way retained its leukotoxic activity. Both hemolytic and leukotoxic activities copurified at the same ratio and were inactivated to the same degree by heating at 56°C. Lysis of leukocytes, if it occurs in vivo, would enhance the chances of survival for an invading hemolytic E. coli.