[Contamination of fermented milk products by proinflammatory autacoid paf-acether]

Paf-acether (platelet-activating factor) is one of the most potent inflammatory mediators synthesized by and acting on most inflammatory cells. It also displays potent immunoregulatory properties. Two metabolic steps are involved in its biosynthesis: the action of a phospholipase A2 on membrane alkyl-acyl (long chain) phospholipids with choline polar head results in the production of lyso paf-acether, and acetylation of the lyso compound by an acetyltransferase yields the biologically active molecule. Recently we showed that E. coli and other bacteria are able to produce paf-acether using exogenous lyso paf-acether. This finding prompted us to search for the presence of paf-acether in fermented milk products. The fraction corresponding to paf-acether isolated from milk exhibited the same physicochemical and biological characteristics as synthetic paf-acether and that from eukaryotic cells. The presence of a biologically active phospholipid in fermented products may bring new perspectives with respect to the study of gastrointestinal diseases as well as the putative immunostimulating effect of yogurt.