Effect of bacterial lipopolysaccharide on bovine polymorphonuclear neutrophil migration in vitro

The in vitro effects of Escherichia coli 026:B6 lipopolysaccharide (LPS) on random migration of bovine polymorphonuclear neutrophils (PMN) was investigated. Treatment of peripheral blood leukocytes (PBL) with LPS significantly inhibited PMN migration. These inhibitions were observed at a threshold concentration of 5.0 micrograms/2.0 X 10(6) PBL. PMN migration inhibition was eliminated in PBL by the addition of polymyxin B, which binds the Lipid A moiety of LPS. Treatment of isolated PMNs with LPS significantly enhanced migration. Enhanced migrations were observed at threshold concentration of 2.5 micrograms/4.0 X 10(6) PMN. Collectively these findings indicate that the inhibition was caused by leukocyte inhibitory factor (LIF) production in PBL cultures, whereas enhancement was probably caused by PMN activation. These results provide further insight into the effects of LPS on in vitro bovine PMN migration by its distinct actions on different cells of PBL.