Table 7.

Allergen components helpful in establishing the indication for AIT (major allergens ^a versus panallergens ^b )

Major allergensa

Bet v 1 ➾ Birch, Betula pendula (formerly Be tula ve rrucosa)

Phl p 1/5 ➾ Grasses, Ph leum p ratense (timothy grass)

Der p 1/2 ➾ House dust mites, Der matophagoides p teronyssinus

Alt a 1 ➾ Alternaria, Alt ernaria a lternata

Ole e 1 ➾ Ash – no actual components instead due to high cross-reactivity: olive tree: Ole a e uropaea

Art v 1 ➾ Mugwort, Art emisia v ulgaris

Amb a 1 ➾ Ragweed, Ambrosia artemisifolia (common ragweed)

Components that explain positive skin tests but are not valid in the indications for AIT (panallergensb)

Profilins: e.g.: Amb a 8 (ragweed), Ara h 5 (peanut), Bet v 2 (birch), Cor a 2 (hazelnut), Hev b 8 (latex), Phl p 12 (grass), Tri a 12 (wheat)

Polcalcins: e.g.: Aln g 4 (alder), Amb a 9 (ragweed), Art v 5 (mugwort), Bet v 4 (birch), Phl p 7 (grass)

^a The name of an allergen component is derived from the first three letters of the genus and the first letter of the species names, e.g., timothy grass Phleum pratense ⇨ Phl p 1. The numbering often follows the chronological order of first description; thus, identical numbers unfortunately do not automaticallysignify cross-reactivity. Cross-reactivity is so high in some allergen-families that it is not necessary to determine the individual components separately: Beech-like (PR10 proteins): Bet v 1 (birch) ⇦⇨ Aln a 1 (alder) ⇦⇨ Cor a 1 (hazelnut); Grasses (grass group 1 allergen): Phl p 1 (timothy) ⇦⇨ Cyn d 1 (Bermuda grass) ⇦⇨ Lol p 1 (ryegrass) ⇦⇨ Tri a 1 (wheat); House dust and flour mites: cysteine proteases, Der p 1 ⇦⇨ f1, NPC2 family: Der p 2 ⇦⇨ f 2. The up-to-date, international WHO/IUIS list of all allergen components is available at: www.allergen.org.

^b Definition: a major allergen is an allergen component to which more than 50% of sensitized allergy sufferers exhibit specific IgE (e.g., in grass allergy: major components, Phl p 1, 2, 5, 6; minor component: Phl p 11). Panallergens are found in many species and are generally clinically insignificant, but nevertheless explain irrelevant positive extract-based skin and/or blood tests, e. g., profilins from 48 plant species are currently described, and new ones are being added daily; for an up-to-date list see: www.meduniwien.ac.at/allergens/allfam.