An evaluation of the sensitivity of subjects with peanut allergy to very low doses of peanut protein: a randomized, double-blind, placebo-controlled food challenge study.
BACKGROUND
The minimum dose of food protein to which subjects with food allergy have reacted in double-blind, placebo-controlled food challenges is between 50 and 100 mg. However, subjects with peanut allergy often report severe reactions after minimal contact with peanuts, even through intact skin.


OBJECTIVE
We sought to determine whether adults previously proven by challenge to be allergic to peanut react to very low doses of peanut protein.


METHODS
We used a randomized, double-blind, placebo-controlled food challenge of 14 subjects allergic to peanuts with doses of peanut ranging from 10 microg to 50 mg, administered in the form of a commercially available peanut flour.


RESULTS
One subject had a systemic reaction to 5 mg of peanut protein, and two subjects had mild objective reactions to 2 mg and 50 mg of peanut protein, respectively. Five subjects had mild subjective reactions (1 to 5 mg and 4 to 50 mg). All subjects with convincing objective reactions had short-lived subjective reactions to preceding doses, as low as 100 microg in two cases. Five subjects did not react to any dose up to 50 mg.


CONCLUSIONS
Even in a group of well-characterized, highly sensitive subjects with peanut allergy, the threshold dose of peanut protein varies. As little as 100 microg of peanut protein provokes symptoms in some subjects with peanut allergy.
Hourihane JO'B
University Child Health, Southampton General Hospital, England.
Kilburn
S A
SA
Nordlee
J A
JA
Hefle
S L
SL
Taylor
S L
SL
Warner
J O
JO
D000328:Adult; D010367:Arachis / Q000009:adverse effects; D004306:Dose-Response Relationship, Immunologic; D004311:Double-Blind Method; D005260:Female; D005433:Flour / Q000009:adverse effects; D005512:Food Hypersensitivity / Q000209:etiology / Q000276:immunology; D006801:Humans; D008297:Male; D010919:Placebos; D014674:Plant Proteins, Dietary / Q000008:administration & dosage*; D014581:Urticaria / Q000209:etiology
D010919:Placebos; D014674:Plant Proteins, Dietary