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Allergen specific immunotherapy


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Allergen specific immunotherapy

  1. 1. Allergen specific immunotherapy Eman youssif
  2. 2. Allergen immunotherapy Allergen immunotherapy (also termed desensitization) is a medical treatment aiming at patients suffering from allergies that are insufficiently controlled by symptomatic treatments.
  3. 3. Sublingual immunotherapy Sub-lingual immunotherapy is used by physicians in many countries: it involves putting drops or a tablet of allergen extracts under the tongue to swallow the extract. It allows the body to become tolerant of the allergen by absorbing the allergen through the stomach lining. The treatment is usually taken at home. Sublingual immunotherapy is currently commercialized and used in most European and South American countries, and in Australia and Asian countries. In most European countries, national regulations allow marketing of allergen products as "named patient preparations" (NPPs). In the United States, it has not yet received FDA approval, though off-label prescription is becoming common.
  4. 4. Subcutaneous immunotherapy Subcutaneous immunotherapy is the historical route of administration and consists of allergen extract injections which can only be performed with a medical observation. Subcutaneous immunotherapy protocols generally involve weekly injections during a build-up phase, followed by monthly maintenance injections for a period of 3–5 years.
  5. 5. History The British physicians Noon and Freeman were the first researchers to test pollen allergen immunotherapy in a patient cohort. Noon and Freeman, researchers at the Department of Therapeutic Inoculation at St. Mary’s Hospital in London, published their findings in The Lancet in 1915.Building on the observations of his predecessors Bostock, Blackley and Dunbar, Noon noted that hay fever patients “sometimes become cured” and that this was possibly because they “have had the good fortune to develop an active immunity against the toxin.” He hypothesized that by injecting hay fever patients with small amounts of a pollen “toxin”, a state of immunity could be achieved.
  6. 6. Mechanism of therapeutic action In desensitization immunotherapy the aim is to restore tolerance to the allergen by reducing its tendency to induce IgE production. Patients are desensitized by injection with escalating doses of allergen, starting with tiny amounts, an injection schedule that gradually decreases the IgE-dominated response. The mechanisms underlying desensitization therapy are complex, but the key to success seems to be the induction of regulatory T cells secreting IL-10 and/or TGF-beta, which skew the response away from IgE production.
  7. 7. Sublingual immunotherapy Sublingual immunotherapy involves, putting drops or a tablet of allergen extract under the tongue and then swallowing the extract. Besides its efficacy, sublingual immunotherapy is known to have a better safety profile than subcutaneous immunotherapy and one of the significant benefits of sublingual immunotherapy .is also that the patient can take the treatment at home Today allergen immunotherapy is available in tablet form (for grass pollens). No other method of administration of allergen immunotherapy has reached this level of proof and provides such a favorable benefit/risk ratio. Allergen immunotherapy has therefore acquired a level of evidence equivalent to that of “conventional” drugs, both in terms of documentation of its pharmaceutical quality and the rigor of its production, and its terms of demonstration of its clinical efficacy and safety for patients.
  8. 8. Subcutaneous immunotherapy Prescribed by an allergy specialist, injections of allergens are administered in a medically controlled environment and followed by an observation period of 30 minutes. These pain-free injections are given in order to subcutaneously (under the skin) administer the allergen on the arm between the elbow and shoulder. Allergen injections are started at very low doses. The dose is gradually increased on a regular (and usually weekly) basis, until a "maintenance" dose is reached. Once the maintenance dose is reached, the injections are administered less often (every two to four weeks), still on a regular basis. After 3 years or 3 seasons (if seasonal allergy) of successful completion of immunotherapy, long- term protection can be expected.
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