An allergen is an antigen, principally a protein, which can elicit symptoms of allergic disease in a previously sensitized individual. This antigen is specifically recognized by the individual's immune system, with subsequent development of specific antibody and/or cell mediated immunity. Fungi can elicit an allergic reaction ranging from mild to severe, anywhere from a stuffy nose, through hay fever and asthma to pneumonitis. In most cases, the physical condition of the host, the amount of allergen the host is exposed to (spores, fungal hyphae, dust, pollen, etc.) and the degree of sensitization of the individual determines the severity of the reaction. In general, common environmental or indoor air contaminating fungi most often affect humans as irritants that elicit an immune response that we generally associate with allergies (hypersensitivity).
or Allergenicity refers to the substance's potential to be an allergen. An allergy is an abnormal reaction to an ordinarily harmless substance called an allergen. Common allergens include pollens, molds, dust mites, animal dander, foods, medications, cockroach droppings, and insect stings/bites. You may be allergic to one or more allergens. When an allergen is absorbed into the body of an allergic person, their body fights to rid itself of the allergen. The immune system initiates a defense which causes symptoms such as runny nose, watery eyes, congestion, itching, and sneezing.