An early exposure of cat allergens and features of the course of allergic rhinitis in children
According to research, cats are extremely popular pets both in the world and in our country. The widespread occurrence of cats leads to the widespread high concentration of their allergens. The role of exposure to cat allergens in the development and course of allergic pathology, according to published data, remains controversial. Most researchers note the protective effect of an early exposure to cat allergens. At the same time, a number of studies have shown an increase in the risk of developing allergic diseases and a decrease in control over their course.
The aim of this study was to identify the relationship between the characteristics of the course of allergic pathology and the age of the first contact with cat allergens.
Material and methods
The study included 228 children living in the Sverdlovsk region. The average age of the children was 8.2 ± 1.9 years, boys dominated in the gender composition – 66.67% (n = 152).
All children were observed by an allergist with a diagnosis of allergic rhinitis (AR). Verification of the diagnosis and assessment of the severity of the course of an allergic disease were carried out on the basis of the clinical recommendations of the Russian Association of Allergologists and Clinical Immunologists (RAACI). The exposure of cat allergens was determined based on personal data on the presence of the animal in the house and the estimated age of the first contact with cats.
Based on the questionnaire data on the first contact with cats, several groups of children were identified: group 1 – 20 patients (8.8%) who had prenatal contact with cats; Group 2 – 67 patients (29.4%) who had contact with cats in the first year of life; 3rd group –
121 patients (53.1%) who had first contact with cats aged 1-3 years; Group 4 – 20 patients (8.8%) who had first contact with cats aged 4 to 7 years.
All children underwent determination of the level of total immunoglobulin E (IgE), serum eosinophilic cationic protein, cytological analysis of nasal secretions, bacteriological examination of a smear from the nasal mucosa. The sensitization spectrum was evaluated on the basis of specific IgE antibodies detected by immunofluorescence using a Phadia-250 instrument (ThermoFisher Scientific, Sweden).
Statistical data processing was carried out using the following parameters: mean value (M), median (Me), standard deviation (σ), mean error of the mean (m). Significance of differences between the compared indices was carried out using the method of one-way analysis of variance using the IBM® SPSS Statistics® 20 software package. Results with a significant difference level of p <0.05 or less were taken into account.
An isolated course of AR was detected in 53 patients (23.2%). Allergic rhinoconjunctivitis (ARC) was observed in 11% of cases (n = 25). The combined course of bronchial asthma (BA) and AR was found in 42.1% (n = 96) of children. Atopic dermatitis (AD) in combination with AR was confirmed in 16.6% (n = 38) of children. In 16 children (7%), a combined lesion of the respiratory system and skin was observed in the form of AD, AR and blood pressure.
AR in all children had a year-round course, in most (65.4%, n = 149), a mild severity of rhinitis was determined. A moderate course of AR was detected in 34.2% (n = 78) of children. One child had a severe course of AR. In most cases (78.6%, n = 88), a mild intermittent or persistent course of AD was observed, in 19.6% (n = 22), a moderate course of the disease was detected, and a severe course in 1.8% (n = 2) . 60.7% (n = 68) of patients had complete control over the course of AD according to the ACT (Asthma Control Test) questionnaire.
Upon contact with cats, 43.4% of patients (n = 99) noted an exacerbation of allergic pathology, manifested by rhinoconjunctival syndrome in 53.5% of children (n = 53). An exacerbation of bronchial obstructive syndrome was detected in 14.1% (n = 14) of children, contact urticaria occurred in 4 patients.
The relative level of eosinophilia in the peripheral blood of the examined children (median and interquartile range) was 5.16% [1.0%; 18.8%]. 30% (n = 69) of children showed an increase in the level of eosinophilic cationic protein. An increase in the content of total IgE was detected in 78.1% of children (n = 178).
All 228 children (100%) revealed the presence of specific IgE antibodies (sIgE) to cat epithelium and dandruff, the serum concentration of which was 36.7 [0.75; 100] kilo units of allergen per liter (KEDA / l). Antibodies to dog epithelium were detected in 24.6% (n = 56) of patients; the median and interquartile range were 10.0 [0.75; 98.2] KEDA / l. In every 4th child (26.3%, n = 60) sIgE antibodies to birch pollen were detected, their concentration was 50.65 [1; 100] KEDA / l.
Eosinophilia in nasal secretions was detected in 33.8% (n = 77) of children, 13.2% (n = 30) had colonization of the nasal cavity with Staphylococcus aureus.
When assessing the nosological structure, as well as the severity of the course of allergic pathology in patients of groups 1–4, no significant differences were found.