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Listen to this siteTuesday 2 March 2004
This research aims to find out if piglets born to mothers that are immunologically sensitive to certain allergens are also sensitive to the same allergens.
Study Duration : March 2002 to August 2006
Contractor : Clinical Veterinary Science, University of Bristol
The number of individuals suffering allergic reactions to food is on the increase, and why this is happening needs to be established. Therefore, this research investigates the critical factors involved in susceptibility and onset of allergy, and which determine the role of in-utero exposure, maternal and weaning diets. This project uses an animal model (pigs) to mimic the in-utero exposure of newborn babies to maternal factors, including dietary antigens found in maternal and weaning diets.
In humans, the transfer of maternal immunoglobulin and antigen occurs in utero via the placenta so that the baby is born with antibodies from the mother. This provides the newborn baby with passive immunity and in the short term will inhibit an active immune response. However, the role of this on long-term active immunity has not been established.
In the pig, maternal transfer in utero of immunoglobulins and antigens does not occur, and so the piglet is solely reliable on colostrum from its mother in order to receive these antibodies. This study uses pigs to determine the effect of a separated maternal antigen experience on the immunology of the offspring.
Newborn piglets are deprived of colostrum and given antigen, antibody or complex directly into their stomachs. Their subsequent immune response to this antigen will be assessed four weeks later.
This project used an animal model to investigate the influence of exposure to food allergens, via maternal sources, on the developing immune system and on allergic outcome.
The pig was chosen as the animal model since pigs in contrast to the human, are born without any maternal antibody or maternally derived dietary antigen (because the pig placenta lacks the ability to transfer large molecules such as proteins). As such, by exposing the pig at birth it is possible to mimic the exposure that occurs in the uterus in humans and to manipulate very early immune exposure.
Newborn piglets deprived of colostrum were exposed (orally) to either egg allergen (ovalbumin), the allergen plus antibody to the protein, or just antibody, at birth. This reflects the different types of exposure which could be experienced by an unborn child in the womb depending on the mother’s diet and immune status.
A further group of newborn pigs were exposed just to saline (control group).
At 16 days of age they were exposed to ovalbumin either by injection or by feeding the allergen and their immune responses monitored using standard immunological assays and tests.
The project found that exposure to high levels (greater than one gram) of the egg ovalbumin protein at birth, with or without the antibody, suppressed any immune response when the pigs were exposed to the protein again at 16 days of age (whether by feeding or injection). Lower doses of 100mg or 1mg had only a marginal or no effect respectively.
Giving antibody alone at birth (whether from pigs injected with the allergen or from animals that had been fed ovalbumin) had no effect on the subsequent immune responses observed in new born pigs to challenge with the allergenic food.
It is important to note that these antibodies were derived from non-atopic pigs who had no observable clinical symptoms when fed ovalbumin.
It is possible that serum from atopic or allergic individuals may induce a different effect.
Pigs given a complex of the antibody plus the egg ovalbumin protein at birth showed little response when subsequently exposed to the allergen at 16 days old indicating that oral tolerance may have been induced.
The results suggest that (in pigs) neonatal antigen exposure induces oral tolerance.
These findings will contribute to our wider understanding of the
possible influence of maternal diet during pregnancy and breastfeeding, on the immune status of the offspring.
The final report is available from the Agency’s Information Centre.
To obtain a copy, please contact the Enquiry Desk, Information Services, Food Standards Agency (tel: 020 7276 8181/8182 or email:
infocentre@foodstandards.gsi.gov.uk
)
For any enquiries concerning this research project, please contact the relevant Programme contact or email: science@foodstandards.gsi.gov.uk
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