A new water-soluble, orally absorbable de-N-acetyl-lysoganglioside (WILD20), breakdown product of the monosialoganglioside GM1, was found to influence some parameters of neutrophil response to inflammation stimuli. Superoxide anion production appears inhibited, along with neutrophil killing properties. A block of both pathways of arachidonic acid cascade and PAF was also found, as well as neutrophil ICAM-1-mediated adhesion to endothelial cells. Of particular interest was the significant reduction of neutrophils observed at the site of inflammation, whichever agonist was used. The effects on neutrophil physiology found in normal or in pathological conditions, are in favour of a WILD20-related inhibitory effect on neutrophil contribution to inflammation.