An allergen can be defined as a substance that has the potential to cause allergies. Allergens are alien particles that target people with a weak immune system though most people are not vulnerable to allergies. Allergens consist of proteins. However, a person can be allergic to almost anything. Protein is found in mostly everything we eat. It is an organic compound that consists of three elements, namely: oxygen, hydrogen, and nitrogen. Protein is an important part of all living beings. An example of an allergen that does not contain proteins is penicillin. It causes an allergic reaction once bound to a protein in the body.
Some common examples of allergens are:
Examples of the less common allergens are:
The immune system of the human body has a responsive mechanism in the form of an antibody known as the "IgE", to invading allergens as they are damaging. When this antibody is releases, it triggers a chain reaction, causing other cells (Mast cells) to release chemicals that result in irritation, inflammation and various other symptoms of allergy.
Among the very common symptoms associated with allergens are:
Basidiospores, the dominant airborne fungal allergens, were considered, back in 1952, as possible airborne allergens; in 1969, they were linked to asthma. Fungal allergy is in fact linked to seasonal asthma. Basidiospores are thought to be one of the primary sources of airborne allergens. Mushrooms, smuts, rusts, puffballs, and brackets are examples of the basidiospores family. The levels of airborne spores from mushrooms and those from mold and pollens are almost the same, whereas the levels of mushroom respiratory allergy are as high as 30% of those with allergic disorder. However, it is believed to be <1% of food allergies. Heavy rainfall increases the release of fungal spore and is linked with increased hospital admissions of asthmatic children. According to a New Zealand study, 22% of patients suffering from respiratory allergic disorders tested positive for basidiospores allergies. Mushroom spore allergies are seen to be responsible for either immediate allergic symptomatology or they can cause delayed allergic reactions. It is more likely that patients with asthma develop immediate allergic reactions, whereas those with allergic rhinitis more likely have delayed allergic responses. Study found that 27% patients were allergic to basidiomycete mycelia extracts and 32% were allergic to basidiospore extracts. This demonstrates the high incidence of fungal sensitization in patients with suspected allergies. Basidiomycete cap, mycelia, and spore extracts are found to be most reliable for diagnosing basidiomycete allergy.
It was found that in Canada, 8% of children attending allergy clinics were allergic to Ganoderma, a basidiospore. Examples of significant airborne spores are Pleurotus ostreatus, cladosporium, and calvatia cyathiformis, whereas aspergillus and alternaria-penicillin families are examples of other significant fungal allergens. In India fomes pectinatis is a predominant air borne allergen that affects about 22% of patients with respiratory allergies. Some fungal air-borne allergens, e.g., coprinus comatus, are linked to the worsening of eczematous skin lesions. Children born during autumn months, when fungal spores are more common, have a higher chance of developing symptoms of asthma later in their life.
Like other types of immunotherapy, such as vaccines, allergen immunotherapy works in the same way. A person who is allergic to a particular substance, is injected with small amounts depending on the condition of the allergy. With time, the quantity of the allergen induced is increased, and improvements in the person's immune system are visible as the body creates antibodies to protect the body from allergens and to defend it from foreign bodies attacking. The effective results of allergen immunotherapy are best seen when used for a period of three to five years.
Allergen immunotherapy is most effective for children. Studies have shown that weekly or monthly injections have been useful in the treatment or prevention of asthma. It is also beneficial for adults, in cases where the medications for an allergy are too strong or have side effects. In general, allergen immunotherapy has two phases: The build-up phase is the first phase that lasts for many months, and in this the patient is injected many times in order to build the body's immune system. The second phase that is also known as the maintenance phase, is for maintaining the person's immune system so that the body's defensive mechanism is able to prevent allergies from recurring. For this, just once a month shots are sufficient but to achieve best results, it must be done over a period of three to five years.
Patients witness fewer allergies upon the completion of allergen immunotherapy. Mostly, the symptoms no longer exist, except in cases of high level allergen exposure. Allergen immunotherapy injections can be used in cases such as insect bites, seasonal allergies, and indoor allergies. Pollen, dust mites, pet dander, mold, and bee stings are the most common allergens. Food allergies cannot be treated using allergen immunotherapy.
Patients are advised to undergo a health examination test to diagnose the right allergen immunotherapy treatment for that symptom. Results vary from patient to patient, and results are seen over a period of one year. Patients are advised to use the medications until they achieve maximum results.
An allergen specialist is required to treat allergies for children as it can be stressful for them to withstand getting injected many times, as in the case of very young children who do not understand the reason for taking these injections. It helps children to relax if the environment is such that they are distracted, and have toys to play with. A detailed explanation should be given to older children of all symptoms and their treatments. However, with frequent visits children become accustomed to the injections.