Multiallergen-Specific Immunotherapy in Polysensitized Patients
Allergen-specific immunotherapy administered by the subcutaneous route was introduced a century ago and has been shown to be effective in the management of allergic rhinitis and asthma. More recently, the sublingual administration of allergen extracts has become popular, especially in European countries, and has also demonstrated efficacy in respiratory allergic diseases. Both modes of allergen administration during immunotherapy have been shown not only to reduce symptoms and the need for medication, but also to prevent the development of additional sensitivities in monosensitized patients, as well as asthma development in patients with allergic rhinitis, with a long-lasting effect after the completion of several years of treatment. Almost all of the well-designed and double-blinded, placebo-controlled studies evaluated treatment with single-allergen extracts. Therefore, most meta-analyses published to date evaluated immunotherapy with single allergen or extracts containing several cross-reactive allergens. As a result, in general, multiallergen immunotherapy in polysensitized patients (mixture of noncross-reactive allergens) is not recommended owing to lack of evidence. Although some guidelines have recommended against the use of multiallergen mixtures, allergists commonly use mixtures to which the patient is sensitive with the rationale that effective immunotherapy should include all major sensitivities. Literature on this subject is scarce in spite of the widespread use worldwide. Here, this issue will be extensively discussed based on currently available literature and future perspectives will also be explored.
Allergen-specific immunotherapy (SIT) administered by the subcutaneous route was introduced a century ago and has been shown to be effective in the treatment of patients with allergic rhinitis (AR) and asthma. More recently, administration of allergen extracts (drops or tablets) by the sublingual route in the management of AR and asthma has become popular with proven efficacy in both AR and asthma.
Both sublingual and subcutaneous routes of allergen SIT have been shown not only to reduce symptoms and the need for medication, but also to prevent the development of new sensitizations in monosensitized patients, and asthma development in patients with AR.
Moreover, both routes have been shown to exert long-term efficacy following completion of several years of treatment.
On the other hand, most of the randomized controlled subcutaneous (SCIT) and sublingual immunotherapy (SLIT) studies have been performed with single allergens or cross-reactive allergen extracts in monosensitized patients, whereas epidemiological and clinical trials show that polysensitization is more prevalent in the general population, and in patients consulting allergists. This high prevalence of polysensitization raised the questions as to whether:
A number of SLIT and SCIT studies published to date have been performed in polysensitized patients treated with monoallergen extracts that have demonstrated clinical efficacy.
On the other hand, the efficacy of multiallergen IT in polysensitized patients has been debated. There have been few studies that have specifically evaluated the efficacy of multiallergen SCIT or SLIT. The available studies on SLIT in polysensitized patients are few with respect to SCIT and are different with respect to the use of allergen mixes and administered doses.
Here, we discuss the evidence for multiallergen IT by both routes in polysensitized patients. Studies using extracts containing several closely related allergens (grass pollen mixture extracts) were considered as single-allergen IT, whereas mixtures or simultaneous treatments with little or no cross-reactivity as multiallergen IT (mites, tree pollens, grass pollens, animal dander and weed pollens).
Abstract and Introduction
Abstract
Allergen-specific immunotherapy administered by the subcutaneous route was introduced a century ago and has been shown to be effective in the management of allergic rhinitis and asthma. More recently, the sublingual administration of allergen extracts has become popular, especially in European countries, and has also demonstrated efficacy in respiratory allergic diseases. Both modes of allergen administration during immunotherapy have been shown not only to reduce symptoms and the need for medication, but also to prevent the development of additional sensitivities in monosensitized patients, as well as asthma development in patients with allergic rhinitis, with a long-lasting effect after the completion of several years of treatment. Almost all of the well-designed and double-blinded, placebo-controlled studies evaluated treatment with single-allergen extracts. Therefore, most meta-analyses published to date evaluated immunotherapy with single allergen or extracts containing several cross-reactive allergens. As a result, in general, multiallergen immunotherapy in polysensitized patients (mixture of noncross-reactive allergens) is not recommended owing to lack of evidence. Although some guidelines have recommended against the use of multiallergen mixtures, allergists commonly use mixtures to which the patient is sensitive with the rationale that effective immunotherapy should include all major sensitivities. Literature on this subject is scarce in spite of the widespread use worldwide. Here, this issue will be extensively discussed based on currently available literature and future perspectives will also be explored.
Introduction
Allergen-specific immunotherapy (SIT) administered by the subcutaneous route was introduced a century ago and has been shown to be effective in the treatment of patients with allergic rhinitis (AR) and asthma. More recently, administration of allergen extracts (drops or tablets) by the sublingual route in the management of AR and asthma has become popular with proven efficacy in both AR and asthma.
Both sublingual and subcutaneous routes of allergen SIT have been shown not only to reduce symptoms and the need for medication, but also to prevent the development of new sensitizations in monosensitized patients, and asthma development in patients with AR.
Moreover, both routes have been shown to exert long-term efficacy following completion of several years of treatment.
On the other hand, most of the randomized controlled subcutaneous (SCIT) and sublingual immunotherapy (SLIT) studies have been performed with single allergens or cross-reactive allergen extracts in monosensitized patients, whereas epidemiological and clinical trials show that polysensitization is more prevalent in the general population, and in patients consulting allergists. This high prevalence of polysensitization raised the questions as to whether:
Monoallergen immunotherapy (IT) is effective in polysensitized patients;
Multiallergen SCIT and SLIT are effective.
A number of SLIT and SCIT studies published to date have been performed in polysensitized patients treated with monoallergen extracts that have demonstrated clinical efficacy.
On the other hand, the efficacy of multiallergen IT in polysensitized patients has been debated. There have been few studies that have specifically evaluated the efficacy of multiallergen SCIT or SLIT. The available studies on SLIT in polysensitized patients are few with respect to SCIT and are different with respect to the use of allergen mixes and administered doses.
Here, we discuss the evidence for multiallergen IT by both routes in polysensitized patients. Studies using extracts containing several closely related allergens (grass pollen mixture extracts) were considered as single-allergen IT, whereas mixtures or simultaneous treatments with little or no cross-reactivity as multiallergen IT (mites, tree pollens, grass pollens, animal dander and weed pollens).
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