title: What makes an allergen an allergen.
mesh_terms: D000485:Allergens; D004781:Environmental Exposure; D000939:Epitopes; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D007073:Immunoglobulin E; D007136:Immunoglobulins; D008970:Molecular Weight
chemical_list: D000485:Allergens; D000939:Epitopes; D007136:Immunoglobulins; D007073:Immunoglobulin E