Minor cat allergens (Fel d 2-8)

Minor cat allergens represent a diverse group of proteins from Felis catus that contribute to allergic sensitization in humans, distinct from the primary major allergen Fel d 1. This group includes Fel d 2 (serum albumin), Fel d 3 (cystatin), and several lipocalins such as Fel d 4 and Fel d 7, which are found in cat saliva, dander, and fur (WHO/IUIS Allergen Nomenclature, 2023). While these proteins are classified as minor because they typically affect a smaller percentage of the allergic population or elicit lower IgE titers than Fel d 1, they are clinically significant for their role in cross-reactivity and severe respiratory symptoms (Smith et al., 2004; Hilger et al., 1997). For instance, Fel d 2 is associated with pork-cat syndrome due to cross-reactivity with porcine albumin, while Fel d 4 is a potent inducer of asthma in sensitized individuals (Posthumus et al., 2013). In a therapeutic context, these allergens are components of standardized cat dander extracts used in allergen-specific immunotherapy (AIT), which aims to desensitize the immune system by inducing regulatory T-cell responses and reducing Th2-mediated inflammation (Moingeon, 2013). Understanding the profile of minor allergens is crucial for precision medicine in allergy, allowing for component-resolved diagnostics to tailor treatment strategies for patients who do not respond to Fel d 1-centric therapies (Kleine-Tebbe & Jakob, 2015).

Other names

Fel d 2Fel d 3Fel d 4Fel d 5Fel d 6Fel d 7Fel d 8Cat serum albuminCat lipocalinCat cystatinCat immunoglobulin

Allergen-specific immunotherapy (AIT) involves the controlled administration of allergen extracts to induce peripheral T-cell tolerance, promote the production of regulatory T-cells (Tregs), and shift the immune response from a Th2-mediated allergic profile to a Th1-mediated or tolerant profile.