The Principle of Homologous Groups in Regulatory Affairs of Allergen Products – A Proposal

Abstract

Among other legal regulations, the Note for Guidance on Allergen Products CPMP/BWP/243/96 released by the European Medicines Agency provides regulatory instructions regarding the quality of allergen extracts for diagnostic or therapeutic purposes. The current revision of this guideline intends to transform the so-called ‘principle of taxonomic families’ to the ‘principle of homologous groups’. According to this concept, the data of one allergen extract demonstrating stability, efficacy and safety can, to a limited extent, be extrapolated to other allergen extracts belonging to the same homologous groups. The present work proposes the formation of homologous groups for pollen species and animal-derived materials on the basis of similar biochemical composition and homology/cross-reactivity of allergens or allergen sources. Some tree pollen species could be assigned to three different homologous groups, some weed pollen species to one homologous group and numerous grass pollen species to one homologous group on condition that data rely on single defined representative species. A homologous group for mites is limited to the Dermatophagoides species and the grouping of vertebrate-derived materials such as dander could be possible under restrictions. The criteria for the formation of the proposed homologous groups are illustrated in detail to provide an opportunity for extending existing homologous groups by further species in case of new insights in allergens and cross-reactivity of allergen sources. In this way, the concept of homologous groups could serve as a dynamic tool in the regulation of allergen products.

Relevance of Allergenic Sensitization to Cynodon dactylon and Phragmites communis: Cross-reactivity With Pooideae Grasses

“…Several publications have described the lack of group 2 and 5 allergens in C dactylon [16], although they are mentioned in Allergome. Only Cyn d 1 and Cyn d 7 have been found to exhibit some cross-reactivity with other grasses, but the results are not consistent [9]. Moreover, group 1 allergens in C dactylon have different epitopes to group 1 allergens in Pooideae grasses [1,17].…”

“…Membership of this group is based on the presence of 3 allergen families: group 1, 2, and 5 [9]. Cross-reactivity studies with different species have shown that the majority of Pooideae species are highly cross-reactive [10][11][12].…”

“…Cross-reactivity studies with different species have shown that the majority of Pooideae species are highly cross-reactive [10][11][12]. C dactylon is not included in this homologous group because it shows limited cross-reactivity with other grasses [9]. There have, however, been recent calls for the inclusion of C dactylon in this group, but considering only the allergen Cyn d 1 [13].…”

Generation and purification of monoclonal antibodies against Der f 2, a major allergen from <i>Dermatophagoides farinae </i>

“…Currently, there are nearly 30 kinds of allergenic components in HDM that have been cloned and identified (7). Approximately 80% to 100% of HDM allergic patients respond to group 1 and group 2 allergens (8).…”

Detection of group 2 Dermatophagoides pteronyssinus allergen for environmental monitoring of dust mite infestation

“…At least 22 allergenic components in house dust mites have been cloned and identified (4). Among them, more than 80% of the HDM-allergic children with asthma have positive skin test reactions to group 1 and group 2 (Der p 1 and Der p 2) (5).…”