The results of the first successful U.K. study into oral tolerance involving severe peanut allergies have been announced by the Department of Allergy, Addenbrooke's Hospital, Cambridge.

In a small study led by Dr. Andrew T. Clark, peanut oral immunotherapy (OIT) was investigated as to whether it could induce clinical tolerance to peanut protein in four peanut allergic children.

Immunotherapy is a treatment strategy that aims to desensitise the immune system by gradually increasing dose of the substance to which a person is allergic to.

The initial examinations confirmed both allergy and dose threshold, i.e. the amount of protein required to cause a reaction. The preliminary assessments revealed a dose threshold of 5-50 mg (1/40-1/4 of a whole peanut). The dose increases were medically supervised at the Wellcome Trust Clinical Research Facility. During the trial one subject had anaphylaxis and required adrenaline.

It is important to note that this study was done under medical supervision and should not be tried at home!

The introductory daily dose of 5mg of peanut flour was gradually increased every 2 weeks to a final dose of 160 times the starting dose (800mg), the equivalent of 5 peanuts. After 6 further weeks of treatment, the oral challenge was repeated to define change in dose threshold.

There were no further incidents of anaphylaxis and each subject tolerated at least 10 whole peanuts (approximately 2.38 g protein) an increase in dose threshold of at least 48, 49, 55 and 478-fold for the four subjects. This demonstrated a substantial increase in dose threshold, more than what would be likely to be ingested accidentally.

This research could prove to be of great consequence to the many allergy sufferers who are affected by their conditions on a daily basis. According to Professor Jonathan Hourihane (Professor of Paediatrics and Child Health, National University of Ireland, Cork) there are 16,000 Irish children affected by peanut allergies. The results of the study indicate that a treatment may potentially be developed that would confer protection against the severe and sometimes fatal allergic reactions caused by the accidental ingestion of peanuts.

However, further and larger studies are still required to determine how frequently immunotherapy must be given to maintain peanut tolerance in children and whether a similar treatment will work for adults.

S.O.