What’s a “threshold”? OIT was designed by researchers to find the common thresholds where doses could be administered without reaction. Starting in the late ’90’s there were studies to understand this sensitivity. Here’s a 1997 study: “As little as 100 micrograms of peanut protein provokes symptoms in some subjects with peanut allergy.”
1997:”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.”
Study: http://www.ncbi.nlm.nih.gov/pubmed/9389287
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.
CONCLUSION: 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.
You can see similar studies on the right side:
The distribution of individual threshold doses eliciting allergic reactions in a population with peanut allergy. [J Allergy Clin Immunol. 2002] http://www.ncbi.nlm.nih.gov/pubmed/12464959
Review: A consensus protocol for the determination of the threshold doses for allergenic foods: how much is too much? [Clin Exp Allergy. 2004]
http://www.ncbi.nlm.nih.gov/pubmed/15144458
Review: Update on threshold doses of food allergens: implications for patients and the food industry. [Curr Opin Allergy Clin Immunol…] http://www.ncbi.nlm.nih.gov/pubmed/15126945
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Even as recently as 2015 these studies continue:
“Researchers studied 436 Europeans with at least one of the most common food allergies, which are peanut, hazelnut, celery, fish, or shrimp. They gave them small doses of the foods they were allergic to and closely monitored their reactions. The people who were most sensitive to allergies could only handle between 1.6 and 10.1 milligrams of peanut, hazelnut, and celery. For fish, there was a higher tolerance of 27.3 milligrams, and people with shrimp allergies could handle the greatest dosage at 2.5 grams.”
Threshold clinical study
http://www.medicaldaily.com/food-allergies-tested-identify-danger-threshold-why-isnt-there-cure-yet-317274
