Sensitisation to furry animals: diagnostic challenges

Background. The problem is of outstanding importance since sensitisation to furry animal allergens (FAA) has been increasing rapidly over the last decade, and it is considered a risk factor for the occurrence and development of respiratory allergic diseases such as asthma and/or rhinitis in sensitised individuals. Studies show that precise diagnosis to FAA is challenging due to unexpected sensitisation to minor allergens, which can be identified by molecular component analysis. Still, it remains unknown in which cases molecular testing is appropriate. Aim. The study aimed to evaluate and compare sensitisation profile results received by two in vitro techniques: molecular component (MC) analysis and allergen extracts (AE). Methods. 55 adult patients (aged 20–60) with allergic rhinitis and/or allergic asthma and/or atopic dermatitis who are sensitised to the most common inhaled allergens (identified by Skin Prick test) were included in the study. Specific IgE (sIgE) assays were performed using different in vitro systems: AE (Euroline, Euroimmun, Germany) and MC (Alex2, MAD GmbH, Austria). The agreement between MC and AE techniques was evaluated by Cohen‘s Kappa coefficient. Results. According to two in vitro assays results, 28.00% (MC) vs 22.00% (AE) of studied subjects were sensitised to animal allergens, of which 46.43% vs 38.10% to cats and dogs, 21.43% vs 23.81% to cats, dogs, and horse and 14.29% vs 9.42% monosensitised to dogs. It was determined that patients monosensitised to cat allergens were 10.71% (MC) vs 28.57% (AE). Only one patient was monosensitised to horse allergen Equ c 1. The most commonly identified molecular components of cat allergens were Fel d 1 (67.86%) and Fel d 7 (32.14%). Can f 5 and Can f_Fd 1 components of dog allergens were the most prevalent (53.57% and 32.14%, respectively). The concordance between results of MC and AE techniques in the determination of sensitisation profile to FAA varied from poor (in patients, monosensitised to minor dog allergen components: Can f 5, Can f_ Fd 1 (ê = 0.241, p = 0.056; 0.321 (p < 0.001)) to very good (in patients sensitised to the main allergens: Can f 1 (from dog, ê = 0.825, p < 0.001) and Fel d 1 (from cat, ê = 0.882; p < 0.001)). sIgE against dog AE was not identified in patients monosensitised to MC Can f d 1 or Can f 5. Conclusions. When patients are sensitised to the major furry animal allergens testing with allergen extracts is sufficient for diagnosis. However, additional molecular component analysis is required when sensitisation to minor allergen is present.