Effect of purified staphylococcal leukocidal toxins on isolated blood polymorphonuclear leukocytes and peritoneal macrophages in vitro

Bicomponent (fractions S and Fl staphylococcal leukocidal toxins (Panton-Va lentine leukocidin-Luk and haemolysin gamma-Hlg) were tested for in vitro a ctivity against isolated polymorphonuclear leukocytes (PMNL) and peritoneal macrophages (PMF). For assessment of membrane permeability at subcytolytic concentrations of leukocidin (Luk-S + Luk-F) and haemolysin gamma (HlgA HlgB) (8-1000 ng/ml), PMNL and PMF were radiolabelled (Rb-86, C-14-amino-is obutyric acid (AIB) or Cr-51). All toxins tested caused lysis oi human PMNL , although considerable differences were noted in the sensitivity of these cells to Luk and Hlg. Release of Cr-51 (at 1000-5000 ng/ml), being a sign o f irreversible cell damage and lysis, was preceded, at lower concentrations of the toxins (40 and 200 ng/ml), by the release of large amounts of low-m olecular labels - Rb-86 and C-14-AIB. In another experiment, it was found t hat release of Rb-86 from PMNL incubated with low concentrations of Luk (50 ng/ml) took place after 15-30 minutes of incubation, when no significant a mounts of C-14-AIB or Cr-51 were released. These findings support the conce pt of pore formation by staphylococcal leuliocidal toxins in membranes of s ensitive cells and indicate that a relatively short time is needed for the formation of these pores after binding of the Luk-S and Luk-F components to the membrane.