Factors Influencing the Allergenicity and Adjuvanticity of Allergens

Stephan Deifl; Barbara Bohle

Disclosures

Immunotherapy. 2011;3(7):881-893. 

In This Article

Abstract and Introduction

Abstract

IgE-mediated allergic disorders affect up to 25% of the population in industrialized countries and result in a Th2-polarized immune response to innocuous environmental proteins, so-called allergens. Among a large number of proteins to which humans are exposed to, only a minute fraction are allergens. This observation suggests that allergens share special features of allergenicity (i.e., the capacity to induce the production of specific IgE antibodies in susceptible individuals). However, the question 'what makes a protein allergenic' still remains unanswered although some biochemical characteristics of allergens and their capacity to interact with the innate immune system could be associated with their allergenic potential. Allergen-specific immunotherapy aims at an alteration of the disease-eliciting immune response by repeated administration of allergens. Recently, approaches emerged to endow allergens with adjuvanticity, in particular aiming at an increase of their immunomodulatory capacity. This article summarizes factors of allergenicity and introduces recent concepts of adjuvanticity to improve allergen-specific immunotherapy.

Introduction

This article will address two 'hot topics' in allergy research, namely allergenicity and adjuvanticity of allergens, in order to reveal what makes proteins allergenic and how allergens can be modified to improve vaccines for allergen-specific immunotherapy. Allergens are harmless, nonpathogenic agents that usually do not elicit relevant immune responses in the majority of human individuals. However, in certain individuals, allergens induce the production of specific IgE antibodies that may mediate clinical reactions. The ability to induce IgE production is termed 'allergenicity'. This article will give an overview on different features of allergens that may determine their allergenicity. However, we need to point out that none of the discussed characteristics can presently be regarded as a common factor for allergenicity. Most of the so-far described characteristics also apply to various proteins that do not cause allergy. The second part of the article covering 'adjuvanticity' will introduce scientific concepts on how to modify allergens in order to increase and guide their immunological potential. In particular, the addition of intrinsic adjuvanticity to allergens by engineering recombinant allergen–adjuvant fusion proteins is a promising approach for vaccine development in allergen-specific immunotherapy.

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