Allergen Immunotherapy in Allergic Respiratory Diseases

Abstract

Over the past 2 decades, the prevalence of allergic respiratory diseases has increased, in part refl ecting changes in lifestyle and environment that promote a T-helper (Th) 2 cell phenotype. 1 It has been estimated that up to 20% of the US and Western Europe populations may be affl icted by allergic respiratory diseases. 2,3 A recent estimate of the total national medical expenditure attributable to adult asthma was reported as $18 billion, with the largest contributors being prescription drugs and inpatient hospitalizations. 4,5 Although allergen avoidance is an integral component and step of therapy, it is often impractical and insuffi cient. As a consequence, the mainstay of allergic disease management has been pharmacotherapy, especially antihistamines, bronchodilators, and inhaled/intranasal corticosteroids, which are targeted to regulate infl ammation of the upper and lower airways. Although these treatments are effective and, in most cases, safe, they offer no lasting benefi t once treatment is stopped and have limited intrinsic disease-modifying effects. Moreover, it has become apparent that allergic diseases are the result of immune dysregulation and refl ect an impairment in the natural tolerance that develops to allergens. 6,7 Immunotherapy has the potential to modify fundamental, underlying disease mechanisms and to have, Allergen-specifi c immunotherapy (SIT) involves the repeated administration of allergenic extracts to atopic individuals over a period of 3 to 5 years either subcutaneously (SCIT) or sublingually (SLIT) for the treatment of allergic respiratory diseases, including asthma and allergic rhinitis (AR). In studies, SCIT and SLIT have been shown to improve existing symptoms of asthma and AR and to also have the capability to cause disease-modifying changes of the underlying atopic condition so as to prevent new allergic sensitization as well as arrest progression of AR to asthma. Recent evidence suggests that immunotherapy brings about these effects through actions that use T-regulatory cells and blocking antibodies such as IgG 4 and IgA 2, which can then result in an "immune deviation" from a T-helper (Th) 2 cell pattern to a Th1 cell pattern. Numerous meta-analyses and studies have been performed to evaluate the existing data among these studies, with the consensus recommendation favoring the use of immunotherapy because of its potential to modify existing diseases. Signifi cant adverse reactions can occur with immunotherapy, including anaphylaxis and, very rarely, death. A primary factor in considering SIT is its potential to provide longlasting effects that are able to be sustained well after its discontinuation. Given the signifi cant burden these allergic diseases impose on the health-care system, SIT appears to be a cost-effective adjunctive treatment in modifying the existing disease state. CHEST 2012; 141(5):1303-1314Abbreviations: AR 5 allergic rhinitis; BHR 5 bronchial hyperresponsiveness; PEF 5 peak expiratory fl ow; SCIT 5 subcutaneous immunotherapy; SIT 5 allergen-specifi c...

Severe Asthma: An Expanding and Mounting Clinical Challenge

“…24 However, in severe disease a concern exists that anaphylactic reactions to immunotherapy may have profound effects on already compromised lung function. 29 In addition, like in other diseases, psychological diseases can complicate management of asthma. Depression is common in asthma and its role contributing to disease severity is not well established.…”

Five-grass-pollen sublingual immunotherapy tablet for the treatment of grass-pollen-induced allergic rhinoconjunctivitis: 5 years of experience

“…AIT also appears to prevent the development of new allergen sensitizations and reduce the risk of subsequent asthma in patients with AR [19]. Its benefits may persist for several years following cessation of treatment [20]. The preventive benefits of AIT may be greater if initiated early in the course of the allergic disease [21,22].…”

Chinese Guideline on allergen immunotherapy for allergic rhinitis

“…SLIT is also widely used in China, because it is safe, non-invasive, and can be easily administered at home. Many systematic reviews suggest that both SCIT and SLIT are effective for AR (127,128). Although the indication for SLIT is similar to that of SCIT, SLIT is more suitable for patients who cannot tolerate SCIT because of severe adverse reactions, objection for repeated injection, or hospital visits for injection therapy are inconvenient.…”