Immune mechanisms of food allergy and its prevention by early intervention

- Skin exposure to foods may promote allergy whereas tolerance develops in the gut.
- Local microbiota may influence the balance of tolerance/allergy gut immune responses.
- Early intervention reduces the window-of-risk when children are not protected by tolerance.
- Prevention studies require long-term immunological and clinical follow-up.
- The dilution effect needs to be considered when assessing prevention biomarkers.

The environmental factors driving the increase in food allergies are unclear and possibly involve dual exposure to allergens, microbiome-driven effects or other mechanisms. Until they can be better understood, early intervention aiming at establishing oral tolerance provides an effective way to decrease the window-of-risk when children may develop allergic sensitisation to foods due to the absence of a protective immune response. Thus, the recent LEAP (Learning Early About Peanut allergy) and LEAP-On studies achieved a high level of peanut allergy prevention by early introduction of peanuts in the infants diet and conveyed more information regarding the evolution of IgE and IgG4 antibody responses to food antigens over time.