Cytolytic effect of polylysine on rabbit polymorphonuclear leukocytes.

The cationic polyamino acids polylysine and polyarginine cause a time and concentration dependent lysis of rabbit polymorphonuclear leukocytes. Lysis, measured as LDH release, is preceded by exocytosis, as can be deduced from a higher lysozyme release than LDH release, at short incubation time or with low concentrations of polylysine. The lytic effect of polylysine could be annihilated with the polyanion polyglutamic acid. Monomeric lysine or arginine, or low-molecular-weight polylysine, were not lytic. This indicates that positive charges on a polymeric molecule of sufficient chain length play a predominant role in the interaction. Substances that promote exocytosis cause an increase of lysozyme release and a reduction of LDH release, whereas inhibitors of exocytosis cause the reverse: less lysozyme release and more LDH release. Negatively charged sialic groups on the plasma membrane are not important for the interaction, because their removal does not affect the lytic effect of polylysine on the cell. The possibility that the lipid part of the plasma membrane is the point of attack for the polycations is discussed.