Immunostimulatory potential of beta-lactoglobulin preparations: effects caused by endotoxin contamination.
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.
Brix
Susanne
S
BioCentrum-DTU, Technical University of Denmark, Lyngby, Denmark.
Bovetto
Lionel
L
Fritsché
Rodolphe
R
Barkholt
Vibeke
V
Frøkiaer
Hanne
H
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*
D000485:Allergens; D004731:Endotoxins; D007782:Lactoglobulins; D008894:Milk Proteins