Role of Leucocidin and Triphospho-inositide in the Control of Potassium Permeability

LEUCOCIDIN is a product of Staphylococcus , consists of two proteins and is toxic to the polymorphonuclear leucocytes of rabbit and man. The study of the response of leucocytes to leucocidin has led to the unexpected finding that the changes that occur mimic those in excitable or secreting cells during membrane depolarization or stimulation by hormones 1 . Thus the permeability to cations but not other small molecules increases, protein in the cytoplasmic particles is secreted and calcium is accumulated in vesicles. It is probable that the primary response to leucocidin is the increased permeability to cations 1 . The changes in membrane structure that precede the altered cation permeability during membrane depolarization are unknown and the mode of action of leucocidin may be relevant. The study of the interaction of leucocidin with the isolated leucocyte membrane and with purified phospholipids led us to suggest that the primary action of leucocidin is to change the conformation of triphospho-inositide in the leucocyte surface membrane. This communication provides confirmatory evidence for this hypothesis.