Academic journal article Bulletin of the World Health Organization

Allergen Nomenclature

Academic journal article Bulletin of the World Health Organization

Allergen Nomenclature

Article excerpt

Introduction

Rapid advances have been made in the past few years on allergen characterization and sequence determination by chemical and molecular biological approaches. This is indicated by the list of allergens with known partial or complete amino acid sequences in Table 1. A number of other important allergens are known in addition to those in Table 1 but their sequences are as yet not known. A useful source for known allergens is the Allergen Database (ALBE) in which are compiled their known biochemical and immunological properties together with their sequence data if known (1).

[TABULAR DATA 1 OMITTED]

To take into account these advances, a revision of the current allergen nomenclature system (2) is given below. As in the current nomenclature system, the proposed revisions are for allergens which induce IgE-mediated (atopic) allergy in humans. In addition to the expected thorough immunochemical characterization of any newly discovered allergen, investigators are urged to obtain partial, or preferably complete, sequence data before using the official nomenclature system. Also it is expected that investigators would screen a reasonable population size so as to establish the frequency of response in patients to the newly discovered allergens.

Investigators frequently refer to allergens as major or minor ones. The generally accepted meaning of this terminology is that an allergen is designated as either major or minor depending on whether greater or less than 50% of patients tested have the corresponding allergen-specific IgEs (cf. 3-5).

The revised nomenclature for allergens is given below together with the proposed nomenclatures for (a) allergen genes, mRNAs and cDNAs and (b) recombinant and synthetic peptides of allergenic interest.

Revised nomenclature

(1) Allergens

Allergens are designated according to the accepted taxonomic name of their source as follows: the first three letters of the genus, space, the first letter of the species, space, and an Arabic number. The numbers are assigned to the allergens in the order of their identification, and the same number is generally used to designate homologous allergens of related species. As two examples, Lol p 1 refers to the first pollen allergen identified from Lolium perenne, rye grass, and Cyn d 1 refers to the homologous pollen allergen from Cynodon dactylon, Bermuda grass.

In some instances, the above system of the first 3 letters of a genus and the first letter of a species has to be modified to include an additional letter for designation of the exact genus or species. For example, 4 of the many vespids which can cause insect allergy are Vespula vulgaris, Vespula vidua, Vespula consobrina and Vespa crabo. The homologous major venom allergens, antigen 5s, from Vespula vulgaris and Vespula vidua are both designated as Ves v 5 in the existing nomenclature, and those from Vespula consobrina and Vespa crabo are designated as Ves c 5. To avoid these ambiguities, antigen 5s from Vespula vulgaris and Vespula vidua will be designated as Ves v 5 and Ves vi 5 respectively, and those from Vespula consobrina and Vespa crabo as Ves c 5 and Vesp c 5. In the examples given, the modified nomenclature is used for the allergens from Vespula vidua and Vespa crabo, as the allergens from Vespula vulgaris were characterized prior to those for Vespula vidua and Vespa crabo.

Another example is for allergens from the domestic dog (Canis domesticus) and the mold Candida albicans. To avoid ambiguity, the modified system is used to designate Can d and Cand a allergens from these two sources respectively.

In the current nomenclature system (2) the letters are italicized and the numerals are Roman numerals. In the revised system, only letters of normal type and Arabic numbers are used. The proposed changes conform to the accepted nomenclature used in bacterial genetics (6) and HLA system (7) in that italicized and normal characters are used to represent genotypes and phenotypes respectively. …

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