Allergen-specific Immunotherapy for Atopic Eczema

Updated

Ulf Darsow

Disclosures

Curr Opin Allergy Clin Immunol. 2012;12(6):665-669. 

In This Article

Abstract and Introduction

Abstract

Purpose of review Aeroallergens are relevant eliciting factors of not only respiratory allergy but also atopic eczema in subgroups of patients. Due to a low number of controlled studies, the use of allergen-specific immunotherapy (ASIT) as potentially curative therapy as in respiratory atopic diseases is controversial in treating atopic eczema. This article summarizes theoretical aspects and recent results of clinical trials associated with ASIT in atopic eczema.
Recent findings Literature demonstrates variability in study design and results, but ASIT has potential to improve the course of atopic eczema if type I sensitizations are present. Studies suggest the efficacy of ASIT on eczema not only in house dust mite allergy but also in patients with birch or grass pollen sensitization. In several studies, only defined subgroups of patients with atopic eczema showed positive results of ASIT. A generally good tolerability of ASIT was seen.
Summary Atopic eczema patients with relevant allergies might benefit from ASIT as an additional therapeutic option. Side effects have been overestimated in the past. Hypothetically, the atopy patch test helps to identify an atopic eczema patient subgroup for successful ASIT.

Introduction: Role of Allergens And Allergen-specific Immunotherapy in Atopic Eczema

The chronic inflammatory skin disease – atopic eczema (atopic dermatitis) – affects up to 20% of children and 3% of adults, and is characterized by recurrent intense pruritus and a typically age-related distribution and skin morphology. Atopic eczema shows a genetic predisposition, multiple changes in immune functions, environmental interaction, and a reduced skin barrier function resulting in facilitated contact of allergens with cells of the immune system.[1,2] It has long been known that environmental substances such as aeroallergens (e.g. house dust mite, pollen) can produce flares in some patients with atopic eczema. In approximately 80% of adults with atopic eczema, sensitizations to allergens are demonstrable. Among the allergens found to be relevant, aeroallergens and food allergens (in children) are most important – often aeroallergens cannot be avoided to the necessary extent.[1,2,3] An epicutaneous patch test with allergens known to elicit IgE-mediated reactions, and the evaluation of eczematous skin lesions [atopy patch test (APT), reviewed in[4]] can be used as a diagnostic tool in further characterizing the reactive subgroup of patients. From APT biopsies, aeroallergen-specific T cells have been cloned. These T cells showed a characteristic T-helper type 2 (Th2) secretion pattern initially, whereas 48 h after allergen provocation, a Th1 pattern was predominant. This same pattern is also found in chronic lesions of atopic eczema. Allergen-specific hyposensitization/immunotherapy (ASIT) is an evidence-based method of curative treatment of immediate-type allergic diseases that has been in clinical use since 1911.[5] The immunologic effects of ASIT are not yet completely understood. In short, ASIT induces a shift of immune response from a Th2 to a Th1 pattern, an induction of regulatory T cells, and a reduction of allergen-specific IgE production. Also, simultaneous induction of blocking, allergen-specific IgG antibodies, and a reduction of mediator release by most cells occur. Release of inhibitory mediators [interleukin (IL)-10] may contribute to the effects.[2,3,5,6] ASIT is widely used on an evidence-based background for the treatment of allergic rhinoconjunctivitis, insect venom anaphylaxis, and with increasing frequency in allergic bronchial asthma.[5] It seemed likely that ASIT could also be effective in patients with atopic eczema and accompanying immediate-type sensitizations. On the contrary, use of ASIT in these patients was controversial due to contradictory clinical observations and theoretical immunologic considerations. We reviewed this topic recently using a comprehensive literature search.[3] This article is therefore focused on the most recent references and study data.

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