Feline immunoglobulin A (Fel d 5) and Feline immunoglobulin M (Fel d 6) (Fel d 5 / Fel d 6)

Fel d 5 and Fel d 6 are feline immunoglobulins, specifically cat IgA and cat IgM, respectively, that function as minor allergens in humans. These proteins are primarily found in cat saliva and dander and are notable for carrying the carbohydrate epitope galactose-alpha-1,3-galactose (alpha-gal). This epitope is a significant driver of cross-reactivity between cat allergens and other mammalian proteins, playing a crucial role in alpha-gal syndrome, where individuals develop an allergy to red meat. While Fel d 1 remains the major cat allergen, sensitization to Fel d 5 and Fel d 6 can complicate the diagnosis of cat allergy and contribute to respiratory symptoms like asthma and rhinitis. In a therapeutic context, these molecules are targets for allergen-specific immunotherapy (AIT), which aims to desensitize the patient's immune system to the allergen. Understanding these components is essential for component-resolved diagnosis and for managing patients with complex mammalian meat and pet allergies. They are also relevant in the study of carbohydrate-mediated allergic reactions, which differ from typical protein-based allergies. Clinical management involves identifying specific IgE levels to these components to tailor treatment strategies. Although they are considered minor allergens, their presence in natural cat extracts ensures they are part of the desensitization process in standard immunotherapy. Research continues into the specific role of these immunoglobulins in the feline immune system and their impact on human health.

Other names

Cat IgACat IgMFeline IgAFeline IgMAlpha-gal-containing cat allergens

Allergen desensitization through repeated exposure to increasing doses of the allergen to induce immune tolerance.