Pasteurization of milk proteins promotes allergic sensitization by enhancing uptake through Peyer's patches.
BACKGROUND
The underlying mechanisms responsible for allergic sensitization to food proteins remain elusive. To investigate the intrinsic properties (as well as the effect of pasteurization) of the milk proteins alpha-lactalbumin, beta-lactoglobulin and casein that promote the induction of milk allergy.


METHODS
Alteration of structure and immune-reactivity of native and pasteurized proteins was assessed by gel filtration and ELISA. Uptake of these proteins was compared in vitro and in vivo. The biological effect was assessed by orally sensitizing C3H/HeJ mice with milk proteins followed by a graded oral challenge. Required dose to induce anaphylaxis, symptoms and mean body temperature was recorded. Antigen-specific antibodies and cytokine production by splenocytes were analyzed.


RESULTS
Soluble beta-lactoglobulin and alpha-lactalbumin but not insoluble casein were readily transcytosed through enterocytes in vitro and in vivo. Pasteurization caused aggregation of beta-lactoglobulin and alpha-lactalbumin inhibiting uptake by intestinal epithelial cells in vitro and in vivo. Furthermore, aggregation redirected uptake to Peyer's patches, which promoted significantly higher Th2-associated antibody and cytokine production in mice than their native counterparts. Despite this only the soluble forms of beta-lactoglobulin and alpha-lactalbumin elicited anaphylaxis (following priming) when allergens were administered orally. Aggregated beta-lactoglobulin and alpha-lactalbumin as well as casein required systemic administration to induce anaphylaxis.


CONCLUSIONS
These results indicate that triggering of an anaphylactic response requires two phases (1) sensitization by aggregates through Peyer's patches and (2) efficient transfer of soluble protein across the epithelial barrier. As the majority of common food allergens tend to form aggregates, this may be of clinical importance.
Roth-Walter
F
F
Center of Immunobiology, Mount Sinai School of Medicine, New York, NY 10029, USA.
Berin
M C
MC
Arnaboldi
P
P
Escalante
C R
CR
Dahan
S
S
Rauch
J
J
Jensen-Jarolim
E
E
Mayer
L
L
D000284:Administration, Oral; D000485:Allergens / Q000276:immunology*; D000707:Anaphylaxis / Q000276:immunology; D000818:Animals; D000917:Antibody Formation; D001831:Body Temperature; D002364:Caseins / Q000276:immunology; D016207:Cytokines / Q000276:immunology; D004306:Dose-Response Relationship, Immunologic; D020895:Enterocytes / Q000276:immunology; D005260:Female; D005511:Food Handling / Q000379:methods*; D006358:Hot Temperature; D007768:Lactalbumin / Q000276:immunology* / Q000378:metabolism; D007782:Lactoglobulins / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D016269:Milk Hypersensitivity / Q000276:immunology*; D010581:Peyer's Patches / Q000276:immunology*
D000485:Allergens; D002364:Caseins; D016207:Cytokines; D007782:Lactoglobulins; D007768:Lactalbumin