IMMUNOMODULATION OF HUMAN BLOOD-CELLS FOLLOWING THE INGESTION OF LACTIC-ACID BACTERIA

Because of the lack of data that convincingly show immunomodulatory pr operties of lactic acid bacteria in humans, a study was performed in w hich healthy volunteers were divided into two groups and given a ferme nted milk product supplemented with Lactobacillus acidophilus strain L a1 or Bifidobacterium bifidum strain Bb 12 for 3 wk. Blood was sampled throughout the study to assess changes in lymphocyte subsets or leuko cyte phagocytic activity following consumption of the fermented produc ts. No modifications of lymphocyte subpopulations were detected. In co ntrast, phagocytosis of Escherichia coli sp, in vitro was enhanced aft er the administration of both fermented products. The increment in pha gocytosis was coincident with fecal colonization by the lactic acid ba cteria and persisted for 6 wk after ingestion of the fermented product s. By this time, the fecal lactobacilli and bifidobacteria had returne d to concentrations prior to consumption. Nonspecific, anti-infective mechanisms of defense can be enhanced by the ingestion of specific lac tic acid bacteria strains. These strains can be used as nutritional su pplements to improve the immune function of particular age groups, i.e ., the neonate or the elderly, for which these functions are diminishe d.