The studies under Objective #1 will determine the feasibility of utilizing walnut OIT for tree nut allergic subjects. At present, strict dietary avoidance of food allergens and ready access to self-injectable epinephrine is the standard of care for food allergy. However, this method of care does not work well for all subjects with tree nut allergy. The ubiquity of tree nut containing foods makes the possibility of inadvertent ingestion great; moreover, children and adults are often in circumstances where epinephrine injection would prove logistically difficult. If, however, we can demonstrate that walnut OIT is effective in reducing life-threatening reactions for tree nut allergic individuals, the treatment would provide an immediate and feasible prevention option for averting potentially life-threatening reactions to accidental tree nut exposure (desensitization). Additionally, this treatment may also provide an avenue to cause tree nut allergic individuals to lose their allergic reactivity to tree nuts (tolerance).