An update on molecular cat allergens: Fel d 1 and what else? Chapter 1: Fel d 1, the major cat allergen

Abstract

BackgroundCats are the major source of indoor inhalant allergens after house dust mites. The global incidence of cat allergies is rising sharply, posing a major public health problem. Ten cat allergens have been identified. The major allergen responsible for symptoms is Fel d 1, a secretoglobin and not a lipocalin, making the cat a special case among mammals.Main bodyGiven its clinical predominance, it is essential to have a good knowledge of this allergenic fraction, including its basic structure, to understand the new exciting diagnostic and therapeutic applications currently in development. The recent arrival of the component-resolved diagnosis, which uses molecular allergens, represents a unique opportunity to improve our understanding of the disease. Recombinant Fel d 1 is now available for in vitro diagnosis by the anti-Fel d 1 specific IgE assay. The first part of the review will seek to describe the recent advances related to Fel d 1 in terms of positive diagnosis and assessment of disease severity. In daily practice, anti-Fel d 1 IgE tend to replace those directed against the overall extract but is this attitude justified? We will look at the most recent arguments to try to answer this question. In parallel, a second revolution is taking place thanks to molecular engineering, which has allowed the development of various forms of recombinant Fel d 1 and which seeks to modify the immunomodulatory properties of the molecule and thus the clinical history of the disease via various modalities of anti-Fel d 1-specific immunotherapy. We will endeavor to give a clear and practical overview of all these trends.

Keep the cat, change the care pathway: A transformational approach to managing Fel d 1, the major cat allergen

“…To date, eight cat‐origin allergens have been identified and registered through the World Health Organization/International Union of Immunological Societies (WHO/IUIS) Allergen Nomenclature Sub‐Committee . Fel d 1, a secretoglobin, is the major cat allergen .…”

“…Allergies to cats are the most common mammalian‐origin allergy in humans and affect approximately 1 in 5 adults worldwide . Fel d 1 is the major cat allergen, accounting for up to 96% of human allergic sensitization to cats and 60%‐90% of the overall antigenicity of cats and cat dander …”

Bedroom Allergen Exposure Beyond House Dust Mites

“…Fel d 1 is a member of the secretoglobin family of proteins, and the major Fel d 1 IgE epitopes have been mapped [26–29]. In contrast, Can f 1 is a member of the lipocalin family of proteins [27–29].…”

“…In contrast, Can f 1 is a member of the lipocalin family of proteins [27–29]. More than 90% of cat-allergic individuals react to Fel d 1, whereas reactivity to Can f 1 has been found to be lower and more variable among dog-sensitive patients [24, 26, 27, 29]. Besides these two allergens, other clinically relevant allergens have been identified.…”

“…Novel data on sensitization patterns have emerged from recent studies that have used component-resolved diagnostics to increase knowledge on sensitization profiles and cross-reactivity [28, 49, 54, 55]. Numerous studies have demonstrated that sensitization, especially high pet-specific IgE levels and co-sensitization, are strongly associated with the prevalence, severity and persistence of asthma [5, 26, 49, 54, 56–58]. Among pet-sensitive individuals, increased exposure levels can have considerable public health effects.…”