For the secondary objective, OFC positive patients with documented allergy who undergo OIT for tree-nuts (n=15 for each tree-nut) or sesame (n=15) will be grouped according to OIT outcome. Paired t-tests comparing IgE and IgG4 binding of specific molecular allergens in individual patients before and after treatment will be performed. Additionally, the pre-OIT IgE and IgG4 profiles against particular molecular allergens will be compared between OIT outcome groups by t-test.