Provocative proposal for a revised nomenclature for allergy and other hypersensitivity diseases
Authors: Johannes Ring, Marek Jutel, Nikos Papadopoulos, Oliver Pfaar, Cezmi Akdis
Journal: Allergy (2018)

Occurrence of objectively reproducible symptoms or signs initiated by exposure to a defined stimulus at a dose tolerated by normal individuals. Over the last decades, allergists are engaged more and more in the management (diagnosis, treatment and prevention) of conditions which are not truly "allergic" according to the current terminology. They are regarded as differential diagnoses under a variety of names such as "idiosyncrasy," "pseudo-allergy," "allergy-like reactions," "intolerance," and more. At the moment, the umbrella term for all these conditions including allergy is "hypersensitivity" which then can be further subdivided into allergy, intolerance, idiosyncrasy, etc. Our specialty, however, is called "Allergology." Therefore, logically we should prefer "Allergy" as the wider umbrella term. Note: We are not "hypersensitivitists" but "allergists." We spend a lot of time to exclude half of our patients from our specialty trying to explain them that they are not "allergic" but only "hypersensitive." At first, such a proposal sounds painful to the ears of a generation of allergists who have preached over decades a different nomenclature. Yet, terminology may change and has changed in history. Over the last 2000 years, a variety of terms have been used for the description of phenomena possibly related to allergy; many of them have been forgotten.1 Since the creation of the term "Allergy" by Clemens von Pirquet in his famous essay from July 24, 1906, in the Munich Medical Weekly,2 allergy and related conditions have been defined in various ways over the century. While Pirquet also included decreased reactivity among "allergy," this aspect has been lost. The last revision of allergy nomenclature dates back to the consensus of the World Allergy Organization (WAO) published in JACI 2004.3 With this current terminology, a number of terms have received different meanings than they had had before. As an example may serve the change of meaning of the term "anaphylaxis": earlier when anaphylaxis was defined as "immunologically mediated immediate-type allergic reaction ….," there was a large confusion with clinically similar but not immunologically mediated conditions called "anaphylactoid," "allergy-like," "pseudo-allergic," or "intolerance" reactions. By taking away the "immunological mechanism" from the primary definition of anaphylaxis, things have become much clearer with an "immune" anaphylaxis and a "nonimmune" anaphylaxis. Clinical conditions can be classified in most patients much simpler, and clinicians and researchers have less trouble in naming the clinical diagnosis at the very stage when it occurs. The same is now proposed for the term "Allergy" taking away the immunological mediation for the definition. The new proposal only changes the meaning of one term and adds an adjective to an existing term, when "allergy" will replace the term "hypersensitivity." Allergy Occurrence of objectively reproducible symptoms or signs initiated by exposure to a defined stimulus at a dose tolerated by normal individuals. Immune-allergy or "immunologically mediated allergy" The term "immune-allergy" or "immunological allergy" will cover all conditions which have been called "allergic" until now and can be further subdivided at libitum into IgE-mediated, cytotoxic, immune complex, and types IVa, IVb, IVc, IVd, etc. With this definition, one also could include some "eosinophilic" diseases as a subgroup of "immunological allergy," which are on the rise and at the moment cannot be called "allergic" although there is evidence for hypersensitivity to exogenous stimuli. Nonimmune allergy Occurrence of signs and symptoms of allergy without detectable immunological sensitization. Nonimmune (not immunologically mediated) allergies can be further subdivided into "intolerance" phenomena due to metabolic effects (eg, lactose intolerance) or disturbed transport mechanisms (eg, fructose malabsorption) as well as the often not well understood so-called idiosyncratic or pseudo-allergic reactions. Anaphylaxis An acute generalized potentially life threatening reaction with variable symptomatology comprising more than two organs. Nothing would have to change for this term. The current definition and classification into an immunological versus nonimmune anaphylaxis serves as an example how successful a change in nomenclature can be. SWOT analysis Let us briefly discuss the advantages and disadvantages of the proposed new nomenclature: S (Strengths) The new terminology would make our discipline stronger and broader. W (Weaknesses) Many allergists and people will have to learn new definitions and forget things which we have been preaching over the last decades O (Opportunities) The new terminology allows to include much more diseases and name them very specifically and logically according to the mechanisms involved; this could finally lead to new diagnostic procedures and molecularly targeted therapy and prevention strategies. T (Threats) There will be a wave of opposition from established allergists and allergy societies With this proposal, the authors do not want to prescribe a new terminology to medicine or society. It is meant as a provocative idea to start a discussion with regard to the essence, aims, problems, limitations, and opportunities of our specialty. We are aware that at the moment several committees are discussing allergy nomenclature and are looking forward to an intense friendly discussion.