In vitro cytotoxic effect of alpha-hemolytic Escherichia coli on human blood granulocytes. Inhibition by alpha-hemolysin antibody.

The influence of alpha-hemolysin antibody on the in vitro cytotoxic effect of alpha-hemolytic Escherichia coli bacteria and culture filtrates was investigated. Damage to human blood granulocytes was quantified by measuring the release of chromium 51 from labelled cells in the presence of whole or fractionated plasma containing alpha-hemolysin antibody. Anti-alpha-hemolysin activity was found exclusively in the IgG fraction of plasma. Human plasma contained "natural" alpha-hemolysin antibody to various titers. Vaccination of rabbits resulted in only modest rises in alpha-hemolysin antibody titers. The cytotoxic effect of alpha-hemolytic E. coli bacteria as well as that of bacterial culture filtrates was reduced in a titer-dependent way in the presence of plasma containing alpha-hemolysin antibody. These results indicate that the cytotoxic effect of alpha-hemolytic E. coli is inhibited by alpha-hemolysin antibody.