Multi Immunotherapy to Test Tolerance and Xolair

Inclusion Criteria: * Participant and/or parent guardian must be able to understand and provide informed consent and/or assent as applicable. * Age 4 to 55 years with moderate to severe allergy to milk and/or egg and/or peanut and/or almond and/or wheat and/or cashew and/or sesame seed and/or soy and/or pecan and/or walnut and/or hazelnut * Positive skin prick test result greater than or equal to 6 mm wheal diameter to each allergen OR * ImmunoCAP Immunoglobulin E (IgE) level \>4 kilo Unit/Liter for each allergen and * A clinical reaction during a DBPCFC to small doses of food defined as \< dose of 500 mg food protein * No clinical reaction observed during the placebo (oat) challenge and * If female, must have a negative urine pregnancy test on the same day (using a Clinical Laboratory Improvement Amendment (CLIA) approved urine test) * If female, of child-bearing potential, must agree to be compliant with a medically-approved method of contraception (please see Pregnancy section under Patient Disposition in this protocol) * Plan to remain in the study area of the research center during the trial * Be trained on the proper use of the Epinephrine autoinjector * Avoid open or blinded food challenges to other allergens outside this study Exclusion Criteria: * Inability or unwillingness of a participant/parent/guardian to give written informed consent or comply with study protocol * History of cardiovascular disease * History of other chronic disease (other than asthma, atopic dermatitis, or rhinitis) requiring therapy (e.g., heart disease, diabetes) that, in the opinion of the Principal Investigator, would represent a risk to the participant's health or safety in this study or the participant's ability to comply with the study protocol * A total IgE at screening of \>2,000 kU/L * Previous adverse reaction to Xolair * A history of severe anaphylaxis (defined as requiring intubation or admission to an ICU) to food allergens that will be used in this study * Unstable angina, significant arrhythmia, uncontrolled hypertension, current smokers, chronic sinusitis, or other chronic or immunological diseases that, in the judgment of the investigator, might interfere with the evaluation or administration of the test drug or pose additional risk to the participant. * Current use of oral, intramuscular, or intravenous corticosteroids, tricyclic antidepressants, or betablockers (oral or topical) * Routine use of medication that could induce adverse gastrointestinal reactions during the study * Refusing to sign the Epinephrine autoinjector Training Form * Pregnant or breast feeding women * A history of oat allergy (since oat is the placebo agent in the DBPCFC), or an objective reaction to the screening DBPCFC to oat * Unwilling to avoid all food allergen-containing items except those given as part of the Oral Immunotherapy as well as any other food allergens you are allergic to that are not included in the 10 foods listed in the study * Concurrent/prior use of immunomodulatory therapy (within 1 month) ie, omalizumab, nontraditional forms of allergen immunotherapy (e.g., oral or sublingual) * Severe asthma (2007 National Heart Lung and Blood Institute (NHLBI) Criteria Steps 5 or 6) at time of enrollment * Mild or moderate asthma (2007 NHLBI Criteria Steps 1-4) at time of enrollment with any of the following criteria met: * Forced Expiratory Volume at one second (FEV1) \< 80% of predicted, or FEV1/Forced Vital Capacity (FVC) \< 75%, with or without controller medications (only for age 6 or greater and able to do spirometry) or * Inhaled Corticosteroid (ICS) dosing of \> 220 mcg daily fluticasone (or equivalent inhaled corticosteroids based on NHLBI dosing chart) or * 1 hospitalization in the past year for asthma or ER visit for asthma within the past six months * Use of steroid medications (Intravenous (IV), Intramuscular (IM) or oral) in the following manners * history of daily oral steroid dosing for \>1 month during the past year or * steroid burst course ( 5 or more days) of 1 mg/kg prednisone) course in the past 3 months or * \>2 steroid burst courses in the past year * Use of complementary and alternative medicine (CAM) treatment modalities (e.g., herbal remedies) for atopic and/or non-atopic disease within 90 days preceding rush desensitization at week 8or at any time . * Inability to discontinue antihistamines for the initial day of escalation, skin testing or Oral Food Challenges (OFCs) * Use of investigational drugs within 24 weeks of participation * Past or current medical problems or findings from physical assessment or laboratory testing that are not listed above, which, in the opinion of the investigator, may pose additional risks from participation in the study, may interfere with the participant's ability to comply with study requirements or that may impact the quality or interpretation of the data obtained from the study.