Arachis hypogaea: A plant species of the family FABACEAE that yields edible seeds, the familiar peanuts, which contain protein, oil and lectins.Peanut Hypersensitivity: Allergic reaction to peanuts that is triggered by the immune system.Hypersensitivity, Delayed: An increased reactivity to specific antigens mediated not by antibodies but by cells.Peanut Agglutinin: Lectin purified from peanuts (ARACHIS HYPOGAEA). It binds to poorly differentiated cells and terminally differentiated cells and is used in cell separation techniques.Drug Hypersensitivity: Immunologically mediated adverse reactions to medicinal substances used legally or illegally.Hypersensitivity: Altered reactivity to an antigen, which can result in pathologic reactions upon subsequent exposure to that particular antigen.Alveolitis, Extrinsic Allergic: A common interstitial lung disease caused by hypersensitivity reactions of PULMONARY ALVEOLI after inhalation of and sensitization to environmental antigens of microbial, animal, or chemical sources. The disease is characterized by lymphocytic alveolitis and granulomatous pneumonitis.Skin Tests: Epicutaneous or intradermal application of a sensitizer for demonstration of either delayed or immediate hypersensitivity. Used in diagnosis of hypersensitivity or as a test for cellular immunity.2S Albumins, Plant: A major class of water-soluble seed storage proteins. Many proteins from this class are major PLANT ALLERGENS.Dermatitis, Contact: A type of acute or chronic skin reaction in which sensitivity is manifested by reactivity to materials or substances coming in contact with the skin. It may involve allergic or non-allergic mechanisms.Food Hypersensitivity: Gastrointestinal disturbances, skin eruptions, or shock due to allergic reactions to allergens in food.Hypersensitivity, Immediate: Hypersensitivity reactions which occur within minutes of exposure to challenging antigen due to the release of histamine which follows the antigen-antibody reaction and causes smooth muscle contraction and increased vascular permeability.Dentin SensitivityDinitrofluorobenzene: Irritants and reagents for labeling terminal amino acid groups.Immunoglobulin E: An immunoglobulin associated with MAST CELLS. Overexpression has been associated with allergic hypersensitivity (HYPERSENSITIVITY, IMMEDIATE).Anaphylaxis: An acute hypersensitivity reaction due to exposure to a previously encountered ANTIGEN. The reaction may include rapidly progressing URTICARIA, respiratory distress, vascular collapse, systemic SHOCK, and death.Antigens, Plant: Substances found in PLANTS that have antigenic activity.Allergens: Antigen-type substances that produce immediate hypersensitivity (HYPERSENSITIVITY, IMMEDIATE).