The purpose of this study is to develop a tool to better predict clinical allergy to peanut, so that those who are skin test positive but non allergic will not have to unnecessarily avoid peanut, and those with true allergy can be diagnosed, possibly without oral ingestion challenge, and treated appropriately

Peanut allergy occurs in about 1% of the population. Allergic reactions to peanuts and tree nuts account for the majority of fatal and near fatal food allergic reactions. Currently the only available treatment is complete avoidance of peanut. Despite avoidance, the majority of peanut allergic people will accidentally ingest peanut. Accurate diagnosis is critical, yet often problematic. Current diagnostic methods such as skin and blood tests cannot predict definitively who is allergic and can result in patients being falsely labeled. One such group is children who have never been exposed to peanut as a means of preventing allergy, yet have positive skin tests. The only means of definitively diagnosing this group is with an oral peanut challenge, a potentially risky procedure. Previous studies have demonstrated differences in certain genes and growth factors between peanut allergic and non-allergic individuals. The proposed study has 2 phases. The first phase, almost completed, examines expression of genes and growth factors in defined groups of peanut allergic and non-allergic individuals which should help distinguish between these groups. Peripheral blood mononuclear cells from each patient will be cultured and analyzed for a variety of growth factors and other immune molecules, including mRNA, thought to be important in allergy.

The second phase of this study will involve feeding peanut to individuals with positive skin tests, who have never been peanut exposed. Their blood will be examined before and after the challenge using information from Part 1, and results will be correlated with their ability to tolerate peanut on feeding. This study should enable us to better predict who is truly peanut allergic.

There are four groups of patients in this study. Group 1 consists of individuals who are allergic to peanut. This group of individuals will have a positive skin test to peanut and a previous allergi reaction to peanut. Group 2 consists of indivduals who have a positive skin test to peanut but who are able to ingest peanuts without problems. Group 3 consists of individuals who have a positive skin test to peanut but who have no known ingestion of peanut and who have avoided peanut lifelong for whatever reason (e.g. a strong family history of peanut allergy). Lastly, group 4 consists of control subjects who are negative to the peanut skin test and are able to tolerate peanut without problems.

Inclusion Criteria:

• 5 years of age and older
• Informed consent (Subject has provided an appropriately signed and dated informed consent. An appropriately signed and dated assent must be obtained from the parents or guardian if the subject is a child under 18 years of age.)
• Free of any clinically significant disease, such as uncontrolled asthma, which may interfere with study evaluations

Group 1:

• skin test positive to peanut
• documented clinical history of peanut allergy. A documented clinical history may include symptoms such as hives,swelling of the mouth or tongue, throat closing sensation, shortness of breath, wheezing, lightheadedness, anaphylaxis.

Group 2:

• Positive skin test to peanut
• History of being able to tolerate peanut exposure without problems

Group 3:

• Positive skin test to peanut
• No known ingestion of peanut

Group 4:

• Negative skin test to peanut
• Negative skin test to other food and environmental allergens
• Able to tolerate peanut exposure without problems

Exclusion Criteria:

• Women who are pregnant or nursing
• use of antihistamines or decongestant therapy four days prior to clinic visit
• use of nasal or inhaled corticosteroid in the 1 month period prior to clinic visit
• use of non-steroidal anti-inflammatory drugs (NSAIDS) in the week prior to clinic visit
• Moderate or severe/ uncontrolled asthma (defined as the use of more than 4 puffs of ventolin per day, not including prophylactic medications prior to exercise)
• Symptomatic allergic rhinitis
• Patients who had an acute allergic reaction to food, drugs, and bee sting in the 1 month period prior to clinic visit
• Use of an epi-pen during the past month
• respiratory infection one month prior to clinic visit
• immunotherapy