Characterization of the human neutrophil response to sex pheromones from Streptococcus faecalis

Synthetic analogs of sex pheromones from Streptococcus faecalis and related pheromone inhibitors have been assayed for their possible effects on human neutrophil leukocyte activation. These sex pheromones are hydrophobic peptides that have regulatory roles in bacterial mating behavior leading to intercellular plasmid transfer. Five of the seven peptides tested were chemotactic for neutrophils in the 10(-5) to 10(-6) M concentration range. Exposure of neutrophils to these same peptides induced polarization of the cells and triggered superoxide production. Cross-desensitization experiments suggest that S. faecalis bacterial peptides act via the fMLF-receptor on neutrophils. This conclusion is supported by the results that leukocyte polarization responses induced by synthetic analogs of S. faecalis sex pheromones can be blocked by t-Boc-FLFLF, a known antagonist of fMLF. It is concluded that inflammatory properties of bacterial supernatants, particularly in the case of S. faecalis strains and perhaps in other bacterial genuses, are contributed in part by nonformylated hydrophobic oligopeptides that recognize and act through the fMLF receptor to activate neutrophils.