Sensitization to cat and dog allergen molecules in childhood and prediction of symptoms of cat and dog allergy in adolescence: A BAMSE/MeDALL study

Abstract

Background: Sensitization to individual cat and dog allergen molecules can contribute differently to development of allergy to these animals.

Objective: We sought to investigate the association between sensitization patterns to cat and dog allergen molecules during childhood and symptoms to these furry animals up to age 16 years.

Methods: Data from 779 randomly collected children from the Barn/Children Allergy/Asthma Milieu Stockholm Epidemiologic birth cohort at 4, 8, and 16 years were used. IgE levels to cat and dog were determined by using ImmunoCAP, and levels to allergen molecules were determined by using an allergen chip based on ISAC technology (Mechanisms for the Development of Allergy chip). Allergy was defined as reported rhinitis, conjunctivitis, or asthma at exposure to cat or dog.

Results: Cross-sectionally, IgE to Fel d 1 and cat extract had similar positive predictive values for cat allergy. IgE to Can f 1 showed a higher positive predictive value for dog allergy than dog extract IgE. Sensitizations to Fel d 1 and Can f 1 in childhood were significantly associated with symptoms to cat or dog at age 16 years. Polysensitization to 3 or more allergen molecules from cat or dog was a better longitudinal predictor of cat or dog symptoms than results of IgE tests with cat or dog allergen extract, respectively. Cross-sectionally, cat/dog-polysensitized children had higher IgE levels and more frequent symptoms to cat and dog than monosensitized children.

Conclusions: Sensitization to Fel d 1 and Can f 1 in childhood and polysensitization to either cat or dog allergen molecules predict cat and dog allergy cross-sectionally and longitudinally significantly better than IgE to cat or dog extract.

Keywords: Allergy; Barn/Children Allergy/Asthma Milieu Stockholm Epidemiologic; Can f 1; Can f 5; Fel d 1; ISAC technology; IgE; allergen; birth cohort; cat; children; dog; microarray; pet; prediction; sensitization.

Fig E1

Flow chart of children in the BAMSE cohort study base (n = 4089) and study population (n = 779).

Fig 1

Prevalence (percentage) of IgE reactivity (≥0.3 ISU-E) to cat (A) and dog (B) allergen components at 4, 8, and 16 years of age (n = 779).

Fig 2

Allergen-specific IgE levels (≥0.3 ISU-E) to cat (A) and dog (B) allergens in children with (white box plots) or without (gray box plots) symptoms to cat, dog, or both at 4, 8, and 16 years of age. Median IgE levels per age group (connected dotted lines) and P values are indicated. n, Number of children with positive results (N = 779); NA, not applicable (subgroup number <5 observations).

Fig 2

Allergen-specific IgE levels (≥0.3 ISU-E) to cat (A) and dog (B) allergens in children with (white box plots) or without (gray box plots) symptoms to cat, dog, or both at 4, 8, and 16 years of age. Median IgE levels per age group (connected dotted lines) and P values are indicated. n, Number of children with positive results (N = 779); NA, not applicable (subgroup number <5 observations).

Fig 3

Overlapping IgE reactivity (≥0.3 ISU-E) to cat and dog allergen components and median IgE levels to Fel d 1 (cat), Can f 1 (dog), and Can f 5 (dog) at 4, 8, and 16 years of age. Cat/dog symptom prevalence in the subgroups is shown (n = 779). Blue circles, IgE reactivity (≥0.3 ISU-E) to any cat allergen component: Fel d 1, Fel d 2, or Fel d 4. Green circles, IgE reactivity (≥0.3 ISU-E) to any dog allergen component: Can f 1, Can f 2, Can f 3, Can f 5, or Can f 6.

Fig 4

Longitudinal logistic regression. Crude and adjusted ORs for IgE sensitizations to cat and dog allergen (ISU-E ≥0.3) at 4 and 8 years of age in relation to reported cat/dog allergy at 16 years of age (n = 779). *Adjusted for concomitant sensitization to the other cat or dog components, respectively. For sensitization matrix, see Table E5.

Fig 5

A and B, Likelihood (y-axis, percentage) of reporting symptoms to cat at 16 years of age depending of the number of IgE-reactive cat allergens (Fel d 1, Fel d 2, and Fel d 4) and ImmunoCAP cat extract sensitization (x-axes) at 4 (Fig 5, A) and 8 (Fig 5, B) years of age. C and D, Likelihood (y-axis, percentage) of reporting symptoms to dog at 16 years of age depending of the number of IgE-reactive dog allergens (Can f 1, Can f 2, Can f 3, Can f 5, and Can f 6) and ImmunoCAP dog extract sensitization (x-axes) at 4 (Fig 5, C) and 8 (Fig 5, D) years of age. Numbers, ORs, and 95% CIs are shown (n = 779).