LIPOPOLYSACCHARIDES FROM PERIODONTAL PATHOGENS PRIME NEUTROPHILS FOR ENHANCED RESPIRATORY BURST - DIFFERENTIAL EFFECT OF A SYNTHETIC LIPID A PRECURSOR IVA (LA-14-PP)

When neutrophils are incubated with bacterial lipopolysaccharide (LPS) , they become primed for enhanced release of superoxide anion (O2(-)) in response to stimulation by FMLP. We investigated the human neutroph il-priming activity of LPS from the periodontal pathogens, Porphyromon as gingivalis (Pg), Prevotella intermedia (Pi) and Actinobacillus acti nomycetemcomitans (Aa) in comparison with that of LPS from Escherichia coli (E. coil). The optimum conditions for LPS to prime neutrophils w ere assessed for every LPS and found to be as follows: Neutrophils wer e incubated with LPS in the presence of 10% heat-inactivated plasma an d 1 mM EDTA at 37 degrees C for 30 min and then stimulated with 1 mu M FMLP at 37 degrees-C for 7 min. Under these conditions, half-maximum priming was observed at 6.2 ng/ml Pg-LPS, 45 ng/ml Pi-LPS, 1.5 ng/ml A a-LPS and 1.5 ng/ml E. coli-LPS. The priming activity of each LPS was neutralized by polymyxin B. Anti-CD14 monoclonal antibody inhibited pr iming by all LPS. The priming by Aa-LPS and E. coli-LPS was inhibited by LA-14-PP, a synthetic lipid A precursor IVA, but that by Pg-LPS and Pi-LPS was not. Priming by tumor necrosis factor alpha was not affect ed by polymyxin B, anti-CD14 antibody or LA-14-PP. Gelation of Limulus amebocyte lysate occured at 10 pg/ml Pg-LPS, 30 pg/ml Pi-LPS, 3 pg/ml Aa-LPS and 3 pg/ml E. coli-LPS. Thus LPS from different periodontal p athogens primed neutrophils with different efficacy. The difference in the sensitivity to LA-14-PP among the four LPS tested raises the poss ibility that the mechanism of host response to Pg-LPS or Pi-LPS may be different from that to Aa-LPS or E. coli-LPS.