Cat allergyJ30.4

Allergy to epithelia of cats. S.a. Pet allergy.

The following allergens were found and analysed: Felis domesticus (cat/cat)

• Fel d 1 Uteroglobin (chain 1): Major allergen, marker for sensitization against cat epithelia
• Fel d 2 Serum albumin: minor allergen, cross-reactivity with other animal epithelia
• Fel d 3 Cystatin: minor allergen, was epithelized from the skin of the cat. 10% of cat allergy sufferers react to Fel d 3.
• Fel d 4 Lipocalin Major allergen, second most important major allergen, cross-reactivity with other lipocalins (Can f 6, Equ c 1); 63% of cat allergy sufferers react to Fel d 4.
• Fel d 5w Immunoglobulin A (Note: sensitization may cause late reactions to red meat and severe anaphylactic reactions when treated with cetuximab); sensitization is directed against alpha-gal (see alpha-galactose syndrome).
• Fel d 6w Immunoglobulin M (Note: sensitization may cause delayed reactions to red meat and severe anaphylactic reactions when treated with cetuximab)
• Fel d 7 Lipocalin (from Ebner gland protein): found in saliva and on cat hair (distributed by licking; great homology to Can f 1)
• Fel d 8 Latherin (Latherin-like protein): was identified from the salivary gland. Surface active, surfactant-like properties. Distributed by the cat by licking on the coat.

Sensitization to animal serum albumin may cause cross-reactions to pork (so-called cat-pig syndrome).

The allergens originate mainly from saliva and epithelia of the cat. Here the highest concentration of allergens is found in the face of the cat. The main allergen in cat epithelia allergy is Fel d 1. 90% of cat allergy sufferers are sensitised to the Fel d 1 allergen. Cats produce Fel d1 (and other allergens) in the sebaceous, anal, salivary and lacrimal glands. From there it is transferred to the coat by licking and grooming. Fel d 1 is very small and light (particle size 2-10 µm) and therefore floatable. The cat allergen can therefore spread aerogenically and remains a potential danger for the allergy sufferer for a very long time (possibility of allergic symptoms even in rooms where no cat is present). Adherence to clothes can lead to allergic symptoms in sensitised persons through contact, even without the presence of a cat (visitors with a cat at home cause allergic symptoms, see also dog allergy).

SIT: The causal therapy of cat dander allergy, hyposensitization (specific immunotherapy, SIT) is not recommended at present. see also guideline. Since hyposensitization is a long-term therapy (duration about 3 to 5 years) and in principle should be performed at times of lower allergen exposure, a therapeutic success - at least in cat owners - is questionable.

Recently, an orally effective hyposensitization is also offered (Lofarma: LAIS cat tablet). Note: Not all health insurances cover the costs of hyposensitization against cat allergens!

Experimental:

• Immunotherapy with field d-1 T-cell peptides: This approach is based on the development of short peptides synthesized according to a modular principle (solid phase peptide synthesis). These are allergen-specific, immunodominant T cell epitopes without IgE binding capacity and without inflammation stimulating activities. Conclusive clinical results are lacking for this therapeutic method.
• Immunotherapy with "synthetic peptide immuno-regulatory epitopes" (SPIRE). This therapeutic approach is a further development of immunotherapy with field d-1 T-cell peptides. It is based on the development of a second generation of T-cell epitope-based peptides, the SPIRES. These consist of shorter amino acid sequences, mostly 13- to 17-amino acids, representing the dominant T-cell epitopes of the corresponding allergen. Due to their reduced tertiary structure, these allergens have lost their ability to cross-link IgE and thus activate mast cells and basophilic granulocytes. The first preparation developed on this basis, Cat-PAD, is in clinical development and is in a phase III trial.

Another therapeutic option for cat owners is to feed an antibody against the main allergen Fel d1 -to the cat. Immunoglobulin Y (IgY) derived from bird eggs is available in a ready-to-use product for the cat: Purina PRO PLAN LIVECLEAR cat food. Due to the distribution of cat allergen through saliva on fur and home objects, the reduction of allergen exposure may take some time.

Experimentally, immunotherapy of the cat with a special Fel d 1 vaccination- after vaccination, the cats form neutralizing antibodies against the main allergen they produce Fel d 1.

Until now it was unclear whether contact with cats in childhood protects against sensitization or promotes it. There were contradictory results on this important question. For example, various birth cohort studies show that the risk of sensitization increases with increasing exposure during early childhood. In older children and adults, an opposite effect was postulated: "at high exposure a protective effect would occur".

British scientists from Manchester will evaluate the data of 1004 children in 2018 (Ihuoma H et al. 2018). The authors of this large study showed that early childhood contact with cats significantly increased the risk of sensitization. In most children with cats, sensitization occurred in the 1st year of life. After that the sensitization rate remained largely unchanged.

In contrast to this collective, the sensitisation rate was low in children with no cats in their household during the pre-school period, but increased more with age. In later adolescence there was no difference between the two groups in the prevalence of sensitisation. Possession of a cat significantly increases the risk of sensitisation to -fel d1 and Fel d4, but not to Fel d2.

Basically important is the observation that in "high-risk children" where both parents suffered from atopic disease, the sensitization rate is higher than in children whose parents did not have atopy. Such a correlation can also be demonstrated for sensitisation to other allergens.

Preparation: LAIS-Cat tablet

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