Scientists develop vaccine strategy for peanut allergyBMJ 1999; 318 doi: https://doi.org/10.1136/bmj.318.7188.894 (Published 03 April 1999) Cite this as: BMJ 1999;318:894
Researchers believe that they may be close to developing a new strategy to combat anaphylactic allergies-such as the increasingly common allergy to peanuts-in which doctors induce tolerance using an oral formulation containing a gene from the offending allergen.
Many established allergies have been traditionally treated by immunotherapy, in which subcutaneous injections of progressively increasing doses of purified allergen are given; a strategy that is effective only in some circumstances. Dr Kam Leong, professor of biomedical engineering at the Johns Hopkins School of Medicine in Baltimore, and his colleagues are developing a new strategy for the induction of tolerance to allergens, in which a gene from the main allergen, in this case peanuts, is cloned into a synthetic vector and administered orally (Nature Medicine 1999;5:380, 387-91).
The new strategy is based on protecting the allergen's DNA from digestion by forming a complex with particles of chitosan, a naturally occurring polysaccharide that is an effective vector for the controlled intestinal delivery of many pharmaceutical agents. After ingestion, the polysaccharide adheres to the intestinal walls and can be taken in by cells of the gastrointestinal tract. In the latest study, when the DNA from peanut allergens was administered orally to mice, the severity of anaphylaxis was blunted considerably when the mice subsequently underwent a protocol for sensitisation and induction of anaphylaxis using the peanut allergen.
The findings are still a long way from being used in clinical applications. For example, the authors have not yet studied the efficacy of gene administration in mice that are not already sensitised to a particular allergen, which is likely to be the case in humans who would require treatment. “The immune system of mice is also quite different from that of man,” said Dr Leong. Although peanut allergy is an increasingly important public health problem, its only proved treatment at the moment consists of educating patients to avoid all possible sources of peanuts. However, many accidental exposures occur because of the ubiquitous use of peanut protein in a variety of food products. “One can envision that this model would be an interesting approach to generate mucosal immunity for a variety of antigens,” Dr Leong said. Asthma is one potential application he said, as well as additional food allergies-for example, to milk.