Allergic reactions caused by contact with pets have a negative impact on the health status of a significant portion of the world’s population. The clinical symptoms characteristic of this condition are well-known, although the molecular mechanisms that trigger them remained unclear for a long time.
To study this issue, a large-scale study conducted in Sweden identified the specific microscopic proteins that determine acute respiratory failure. The obtained results explain why allergies to cats and dogs cause severe clinical complications in some cases.
Researchers observed 595 adolescents aged 7 to 19 living in Northern Sweden. Sweden represents an ideal environment for the study, as a low prevalence of dust mites and an abundance of pets are recorded here.
Scientists utilized skin tests, questionnaires, and molecular blood analysis (ImmunoCAP ISAC chip). The goal of the study was to establish the connection between specific allergenic proteins and symptoms such as asthma and irritation of the eyes and nose.
The statistical data are quite noteworthy: allergy to cats is observed in 30.6% of adolescents, and to dogs in 31.1%. In 59% of allergic individuals, sensitivity toward both animals is recorded. Symptoms often manifest in severe forms. During contact with a cat, an asthmatic reaction develops in 8.6% of adolescents, while in the case of a dog, this figure amounts to 5.1%.
However, asthma is only one part of the clinical picture. Although rhinoconjunctivitis occurs 4-5 times more often than asthma, patients suffering from asthma almost always suffer from symptoms of rhinitis.
As a result of molecular research, it was established that the intensity of allergic reactions depends on the structure of various proteins. Cat allergy is characterized by a relatively simple biochemical picture, where Fel d 1 plays the leading role (the mentioned protein determines 90% of reactions).
In the case of dog allergy, the picture is much more complex, because one dominant protein does not emerge. Can f 5(51.6%) and Can f 1 (44%) are distinguished by the highest prevalence, although in 27.3% of adolescents allergic to dogs, the test showed a negative result for all six known proteins. The mentioned diversity indicates that the patient’s condition is often determined by a combination of several different molecules.
Based precisely on this circumstance, the risk of developing asthma increases directly proportionally to the number of allergenic molecules present in the body. In this process, proteins of the lipocalin group play a decisive role. They spread over long distances through the air and are characterized by the ability to penetrate deep into the lungs, which provokes asthmatic reactions. In addition, it is characteristic for them to cause cross-reactions between cats and dogs.
However, not all representatives of this group are equally dangerous. For example, the dog protein Can f 5 is produced only in the prostate gland of the male dog. An allergic reaction toward it is characterized by a relatively mild form and mainly manifests only during direct contact with male dogs.
The mentioned discoveries are shaping new standards of diagnosis and treatment in medicine. Instead of general tests that checked for a reaction to the animal’s epithelium, the focus in clinical practice will shift to the identification of specific proteins (e.g., Fel d 1 or Can f 1).
Source: International Archives of Allergy and Immunology
