Leukocidal toxins of staphylococci.

Leukocidal toxins (synergohymenotropic toxin) are cytotoxins produced by staphylococci (S. aureus and S. intermedius) and consist of two separate components. The toxic effect depends on the synergistic action of two proteins. One of them belongs to class F (e.g. LukF-PV, LukF-R, LukF-I, LukM, HlgB) and the other, to class S (e.g. LukS-PV, LukS-R, LukS-I, HlgA, HlgC). Best known are the toxins produced by S. aureus: gamma-haemolysins, HlgA/HlgB and HlgC/HlgB and leukocidin Panton-Valentine, LukS-PV/LukF-PV (Luk-PV, PVL). Very few data are available concerning the relationship between the production of these toxins and the pathology of staphylococcal infections, because little is known about local and general effects of these leukocidal products in vivo. Frequent isolations of staphylococcal strains producing leukocidal toxins from necrotic skin lesions and furuncles suggest a role of these toxins in the virulence of staphylococci, at least in cutaneous infections. Recent data on mechanisms of cytotoxic effects of staphylococcal leukocidal toxins in vitro as well as effects of leukocidal toxins in vitro are discussed. Cell membranes appear to be a primary target for triggering the lysis of phagocytic cells caused by staphylococcal leukocidal toxins.