Diagnosis of Allergy to Mammals and Fish: Cross-Reactive vs. Specific Markers

Abstract

Purpose of review: Allergen extracts are still widely used in allergy diagnosis as they are regarded as sensitive screening tools despite the fact that they may lack some minor allergens. Another drawback of extracts is their low specificity, which is due to the presence of cross-reactive allergens. Progress in allergen identification has disclosed a number of allergenic molecules of homologous sequence and structure which are present in different animal species. This review summarizes recent advances in mammalian and fish allergen identification and focuses on their clinical relevance.

Recent findings: Serum albumins and parvalbumins are well-known animal panallergens. More recently several members of the lipocalin family were found to be cross-reactive between furry animals whereas in fish, additional allergens, enolase, aldolase and collagen, were found to be important and cross-reactive allergens. New epidemiological studies have analysed the prevalence and clinical relevance of mammalian and fish components. Primary sensitization can be distinguished from cross-sensitization by using marker allergens. Although substantial progress has been made in allergen identification, only few markers are commercially available for routine clinical practice.

Keywords: Allergen component; Allergy diagnosis; Cross-reactive allergen; Cross-sensitization; Fish allergy; Furry animal allergy.

Fig. 1

Symmetric versus asymmetric cross-reactivity. a Allergen 1 and 2 are co-sensitizers. Inhibition of IgE binding to allergen 1 can be partially inhibited by allergen 2 (squares); reciprocally allergen 1 also partially inhibits IgE binding to allergen 2 (circles).b Allergen 1 is the primary sensitization source (sensitizer). The sensitizer (circles) completely inhibits binding to allergen 2 (cross-reactive allergen) whereas allergen 2 (squares) is not able to inhibit IgE binding to allergen 1