Allergic sensitization to bovine beta-lactoglobulin: comparison between germ-free and conventional BALB/c mice.
BACKGROUND
The 'hygiene hypothesis' suggests that high hygienic standards met in western countries lead to a lack of microbial exposure, thus promoting the development of atopy by preventing the proper maturation of the immune system. Germ-free animals are deprived of the immune stimulation that occurs during postnatal gut colonization by commensal bacteria. Germ-free mice could thereby provide an attractive model for studying the impact of gut microbiota on the development of Th2-mediated disorders such as allergy.


METHODS
Germ-free and conventional BALB/c mice were sensitized to beta-lactoglobulin (BLG), a major cow's milk allergen, by means of intraperitoneal injections in the presence of incomplete Freund's adjuvant. Time courses of serum and fecal BLG-specific antibody responses were monitored and cytokine production was assayed in BLG-reactivated splenocytes.


RESULTS
Serum BLG-specific IgG1 and IgE concentrations were significantly higher in germ-free mice during the primary immune response and IgE production persisted longer in germ-free mice. Furthermore, secretion of BLG-specific IgA was evidenced only in feces from germ-free mice while, in contrast, fecal IgG1 concentrations were at least 3-fold higher in conventional mice than in germ-free mice. Production of IL-5, IL-10 and IFN-gamma was 3-fold enhanced in BLG-reactivated splenocytes from germ-free mice.


CONCLUSIONS
The absence of gut microbiota significantly affects the BLG-specific immune response in BALB/c mice, thus suggesting that this model might be of interest for further studies exploring the influence of gut colonization by different bacterial strains on the development of an allergic-type sensitization.
Hazebrouck
S
S
INRA, UR 496, Immuno-Allergie Alimentaire, IBiTecS-SPI, CEA de Saclay, Gif-sur-Yvette, France. Stephane.Hazebrouck@cea.fr
Przybylski-Nicaise
L
L
Ah-Leung
S
S
Adel-Patient
K
K
Corthier
G
G
Wal
J-M
JM
Rabot
S
S
D000818:Animals; D005243:Feces; D005620:Freund's Adjuvant / Q000276:immunology; D005856:Germ-Free Life / Q000276:immunology; D007070:Immunoglobulin A / Q000032:analysis; D007073:Immunoglobulin E / Q000097:blood; D007074:Immunoglobulin G / Q000032:analysis / Q000097:blood; D007371:Interferon-gamma / Q000032:analysis; D016753:Interleukin-10 / Q000032:analysis; D015848:Interleukin-5 / Q000032:analysis; D007782:Lactoglobulins / Q000276:immunology*; D008055:Lipids / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D016269:Milk Hypersensitivity / Q000276:immunology*; D013154:Spleen / Q000276:immunology / Q000378:metabolism
D007070:Immunoglobulin A; D007074:Immunoglobulin G; D015848:Interleukin-5; D007782:Lactoglobulins; D008055:Lipids; C114843:incomplete Freund's adjuvant; D016753:Interleukin-10; D007073:Immunoglobulin E; D007371:Interferon-gamma; D005620:Freund's Adjuvant