Cytotoxic effects of leukocidin from Pseudomonas aeruginosa on polymorphonuclear leukocytes from cattle.

The cytotoxic action of leukocidin from Pseudomonas aeruginosa was studied in vitro by following the release of various intracellular markers from polymorphonuclear leukocytes from cattle (PMLC). Low-molecular markers (K+, 86Rb+, glucose) were lost from PMLC within 1 to 2 min after the addition of leukocytes. The release of high-molecular-weight indicators (51Cr, bound to intracellular protein; lactate dehydrogenase) occurred only after swelling of the cells, leading to an increased permeability of the plasma membrane. Calcium ions stimulated the leakage of granule enzymes but retarded or inhibited the release of cytoplasmic markers. At 4 C, leukocytes were unaffected by the toxin. Leukocidin, bound at 4 C to leukocytes and treated with antiserum against leukocidin, did not damage the cells upon increasing the incubation temperature to 37 C.