The cytotoxic action of leucocidan from Pseudomonas aeruginosa on human polymorphonuclear leucocytes.

Human polymorphonuclear leucocytes treated in vitro with leucocidin from Pseudomonas aeruginosa underwent characteristic morphological alterations as shown by phase-contrast and scanning electron microscopy. Within a few minutes of exposure to leucocidin the granulocytes became round, and protoplasmic extrusions appeared on the cell membrane, were withdrawn again and put out at another point of the cell. The final stage of the leucocidin-treated leucocyte was an enlarged, rounded vesicle with apparently intact plasma membrane. Omission of calcium ions from the diluting buffer caused certain differences in the morphologic appearance of the damaged leucocytes.