The specific aim of this study is to desensitize peanut-allergic subjects with peanut allergen-specific, sublingual immunotherapy (SLIT) by placing drops of peanut protein under the tongue which will be absorbed. The hypothesis is that peanut SLIT will desensitize patients with peanut allergic reactions by changing the subject's immune system to adapt to peanuts.

In spite of increased recognition and understanding of food allergies, food-induced anaphylaxis is the single most common cause of anaphylaxis seen in hospital emergency departments, accounting for about one third of anaphylaxis cases seen. It is estimated that about 30,000 food-induced anaphylactic events are seen in U.S. emergency departments each year and that about 200 fatal cases occur in the U.S. each year. Either peanuts or tree nuts cause more than 80% of these reactions.

The goal of this study is to develop peanut sublingual immunotherapy (IT) for patients with peanut allergic reactions. This study is designed to utilize the extensive knowledge of the allergens involved in peanut hypersensitivity to devise an immunotherapeutic approach that would lower the risk of anaphylactic reactions (systemic IgE-mediated allergic reaction) and would down regulate peanut-specific T cells in peanut-allergic patients.

• Other: Peanut protein
• Other: Glycerol saline drops
• Other: Blood draw and skin tests

• Active Comparator: Subjects who receive the protein at the beginning of the study.
• Placebo Comparator: Subjects who receive placebo at the beginning of the study.
• Other: Control subjects

Inclusion Criteria:

• Peanut IgE > 7kU/L (> 2kU/L for children aged 2 years and under) AND
• History of significant clinical symptoms within 60 minutes after the ingestion of peanuts.

Exclusion Criteria:

• History of severe life-threatening anaphylaxis to peanut,
• Medical history that would prevent a DBPCFC to peanut,
• Unable to cooperate with challenge procedures, or
• Unable to be reached by telephone for follow-up.