title: Immunostimulatory potential of beta-lactoglobulin preparations: effects caused by endotoxin contamination.
abstract: BACKGROUND
  The immunomodulating potential residing in cow's milk proteins is currently receiving increasing attention because of growing interest in functional foods and the complex problem of cow's milk allergy. One of the major cow's milk allergens, whey protein beta-lactoglobulin, has previously been shown to mediate cellular activation in both human and murine immune cells.
  
  
  OBJECTIVE
  We examined the response to different beta-lactoglobulin preparations in naive immune cells.
  
  
  METHODS
  Splenocytes and cells from mesenteric lymph nodes derived from BALB/c mice bred and maintained on a milk-free diet were cultured in vitro with different beta-lactoglobulin preparations. Cell proliferation, cytokine production, and increases in intracellular glutathione were used as cellular activation markers. Moreover, the effect of beta-lactoglobulin on cytokine production in murine bone-marrow-derived dendritic cells was examined.
  
  
  RESULTS
  We observed that some commercial beta-lactoglobulin preparations induced pronounced proliferation of both spleen cells and cells from mesenteric lymph nodes; production of TNF-alpha, IL-6, IL-1beta, and IL-10; and an increased level of intracellular glutathione in spleen cell cultures. Furthermore, TNF-alpha, IL-6, IL-1beta, and IL-10 production was induced in murine bone-marrow-derived dendritic cells. Purification of beta-lactoglobulin from raw milk using nondenaturating conditions, however, revealed that the beta-lactoglobulin per se did not possess the immunomodulatory activity. Eventually, the immunostimulatory effect was found to be caused by endotoxin contamination.
  
  
  CONCLUSIONS
  These results identify endotoxin as the main immunostimulatory component present in some commercial beta-lactoglobulin preparations. Moreover, the present study makes it evident that immunomodulatory effects attributed to beta-lactoglobulin need to be reassessed.
authors.affiliation: BioCentrum-DTU, Technical University of Denmark, Lyngby, Denmark.
authors.forename: Susanne
authors.initials: S
authors.lastname: Brix
authors.forename: Lionel
authors.initials: L
authors.lastname: Bovetto
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Fritsché
authors.forename: Vibeke
authors.initials: V
authors.lastname: Barkholt
authors.forename: Hanne
authors.initials: H
authors.lastname: Frøkiaer
mesh_terms: D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000818:Animals; D004731:Endotoxins / Q000032:analysis* / Q000276:immunology; D005260:Female; D007782:Lactoglobulins / Q000737:chemistry* / Q000276:immunology* / Q000302:isolation & purification; D008198:Lymph Nodes / Q000737:chemistry / Q000276:immunology*; D008213:Lymphocyte Activation; D008643:Mesentery; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D016269:Milk Hypersensitivity / Q000209:etiology; D008894:Milk Proteins / Q000737:chemistry / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000276:immunology*
chemical_list: D000485:Allergens; D004731:Endotoxins; D007782:Lactoglobulins; D008894:Milk Proteins