Binding of the Staphylococcus aureus leucotoxin LukM to its leucocyte targets

摘要: Abstract The range of leucocytes susceptible to the leucotoxin LukM/F′, a two-component pore-forming toxin Staphylococcus aureus causing mastitis in ruminants, had not been defined. We used fluorescent-labeled LukM investigate binding this bovine cells and identify its cellular targets among bovine, human murine leucocytes. bound blood neutrophils from all individuals tested with similar affinity, an apparent dissociation constant (Kd) 1.81 ± 0.14 nM 13 3100 ± 506 sites. amount did depend on presence complementary component LukF’, suggesting that ligand does formation oligomers, number molecules corresponds available cell membrane ligands. Other staphylococcal class S components bipartite leucotoxins (HlgA, HlgC, LukE, LukS-PV) were inefficient competitors for neutrophils, indicating has distinct target cells. Bovine slightly more than milk much ovine caprine neutrophils. monocytes macrophages readily LukM, whereas lymphocytes not. Human little resistant LukM/F′ at highest concentration (40 nM). Murine toxicity exhibiting flattening nucleus alteration beginning 0.3 nM concentration. Among peritoneal exudate cells, T (CD3+) monocytes/macrophages (F4/80+) B (CD19+) was detected. These results indicate myeloid lineage are main dairy resident or inflammatory migrated phagocytes toxin.