title: Enhancing immunity by dietary consumption of a probiotic lactic acid bacterium (Bifidobacterium lactis HN019): optimization and definition of cellular immune responses.
abstract: OBJECTIVE
  To define the cellular basis for immune enhancement by a probiotic lactic acid bacteria strain (Bifidobacterium lactis HN019); and to determine whether immune enhancement can be optimized by delivery in oligosaccharide-enriched low-fat milk.
  
  
  METHODS
  A double-blind, three-stage before-and-after intervention trial.
  
  
  METHODS
  Taipei Medical College Hospital, Taipei, Taiwan.
  
  
  METHODS
  Fifty healthy Taiwanese citizens (age range 41-81; median 60) randomly allocated to two groups.
  
  
  METHODS
  In stage 1 (run-in control stage) all subjects consumed reconstituted low-fat milk (LFM) for 3 weeks; in stage 2 (probiotic intervention) subjects consumed B. lactis in LFM (group A) or B. lactis in lactose-hydrolysed LFM (group B) for 3 weeks; in stage 3 all subjects returned to non-supplemented LFM for a further 3 weeks (washout stage). The innate immune functions of two different leucocyte types (polymorphonuclear (PMN) cells and natural killer (NK) cells) were assessed at four time points via in vitro analyses on peripheral blood samples.
  
  
  RESULTS
  While consumption of LFM alone had no significant effect on immune responses, stage 2 results indicated significantly enhanced PMN cell phagocytosis and NK cell tumour killing activity following consumption of milk containing B. lactis. These increases levelled off following cessation of B. lactis consumption, but remained above the pre-treatment values. Increases in PMN and NK cell activity were greatest among subjects who consumed B. lactis in lactose-hydrolysed LFM.
  
  
  CONCLUSIONS
  Dietary consumption of the probiotic bacterium B. lactis HN019 enhanced immune function of two different types of leucocytes; the degree of enhancement was increased by consuming B. lactis in an oligosaccharide-rich substrate.
  
  
  BACKGROUND
  Financial support was provided by the New Zealand Dairy Board.
authors: College of Medicine, National Taiwan University, Taipei, Taiwan.
authors: B L
authors: BL
authors: Chiang
authors: Y H
authors: YH
authors: Sheih
authors: L H
authors: LH
authors: Wang
authors: C K
authors: CK
authors: Liao
authors: H S
authors: HS
authors: Gill
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001644:Bifidobacterium; D003611:Dairy Products / Q000382:microbiology*; D004032:Diet; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007111:Immunity, Cellular; D007694:Killer Cells, Natural / Q000276:immunology; D007962:Leukocytes / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010587:Phagocytosis; D019936:Probiotics / Q000008:administration & dosage*; D013624:Taiwan