How molecular diagnostics help us to correctly identify pet allergies

Summary

Simultaneous sensitization to two or more animal species is common and represents a regular diagnostic problem during conventional extract-based allergy diagnosis. The use of single allergen molecules reveals the underlying cause of polysensitization and enables the distinction between primary sensitization and cross-reaction as a prerequisite for the selection of appropriate immunotherapy vaccines. Individual sensitization patterns can be valuable predictors of clinical relevance, symptom severity and asthma risk, and in part reflect current or past animal exposure. The concept of “marker allergens” is challenging in the case of pet allergies because many animal allergens are ubiquitous pan-allergens limiting the definition of group-specific markers. Alternatively, quantitative aspects often have to be used to identify the primary sensitizers. A sufficient number of allergen molecules is now available from cat and dog to unravel the many cases of cat–dog double sensitization. There are still substantial diagnostic gaps concerning allergens from small animals and farm animals, or such allergens are only available for multiplex testing. The lipocalins, a particularly species-rich and heterogeneous allergen family comprising important major and minor allergens from virtually all furry animals, show complex cross-reactivity patterns with each other and have been recently identified as a major cause of polysensitization.