Role of T-Cells in Asthma

Study Summary

This study will examine the movement of T cells (a type of white blood cell) from the blood to the lungs in patients with asthma after exposure to an allergen, such as cat dander or pollen. Asthma is in large part due to inflammation of the bronchi (the breathing tubes of the lungs), causing heat, swelling and redness. T cells play a major role in the inflammatory reaction. A better understanding of T cell migration to the lungs after allergen exposure may lead to improved therapies for asthma. Patients between 18 and 50 years of age with mild allergic asthma may be eligible for this study. In addition, patients and healthy normal volunteers between 18 and 65 years of age may participate in a sub-study (blood draw) of this protocol. Participants will undergo the following procedures: Visit 1 (screening visit) * Blood tests for blood counts and HIV * Urine pregnancy test for women of childbearing potential. Visit 2 * Physical examination and electrocardiogram (EKG) * Prick skin testing - A drop of allergen extract is put on the skin and the underlying skin is scratched with a needle. A positive test resembles an insect bite and may itch. * Intradermal skin tests - Increasing concentrations of a drop of diluted allergen are injected into the skin and the allergic response is monitored until a 5-mm swelling (1/4 inch) swelling develops. * Methacholine challenge - The subject has repeated pulmonary function (breathing) tests after breathing methacholine, a drug that temporarily (for 5 to 10 minutes) worsens asthma symptoms. * Physician evaluation and repeat pulmonary function test Visit 3 \- Allergen bronchoprovocation - This test will be done in patients whose physical evaluation and breathing test permit them to continue with the study. A heparin lock (needle device that stays in a vein to allow multiple blood draws without repeated sticks) is placed. The subject breathes 5 breaths of allergen through a nebulizer (device that creates a mist), followed by a brea