Levels of horse allergen Equ c 4 in dander and saliva from ten horse breeds

Horse allergy: Curly Horses can mediate immune tolerance

American Bashkir Curly Horses are claimed to be hypoallergenic, but this has not been clinically proven. In the present study, the effect of exposure to Curly Horses was investigated in 141 patients allergic to horses by measuring their lung function and nasal patency during Curly Horse contact. Continuous contact with Curly Horses, including riding and brushing, decreased the allergic riders' reactivity as measured by FEV1, PEF, and PNIF. Subsequent visits (up to 40 or more hours of riding) further reduced reactivity to the Curly Horses. Allergic events to horses occurred only in 72 out of 1312 riding hours, mainly in the first ten riding hours.In 41 out of the 141 patients, it was further investigated whether repeated exposure to Curly Horses could induce tolerance to other horses. Patients in the tolerance induction study were tested annually for horse allergy using a nasal provocation test. The tolerance induction study showed that exposure to Curly Horses induced immune tolerance to other horses in 88% of patients who completed the study.To understand the mechanism causing hypoallergenicity, we performed IgE immunoblots to determine whether Curly Horse hairs contain IgE binding proteins. However, no differences in IgE reactivity were found between Curly and non-Curly Horses. Moreover, the immune tolerance induction study patients did not show decreased IgE reactivity to hairs from Curly or non-Curly Horses even though patients had developed tolerance. However, we did find increasing levels of anti-horse IgG antibodies in the study patients.Overall, our data strongly suggests that continuous exposure to Curly Horses can induce immune tolerance, rendering these patients non-reactive to horses. The reason for the reduced clinical allergenicity of Curly Horses remains unclear, but the data suggest that blocking IgG antibodies may be of importance for immune tolerance development.

Measurement of Horse Allergens Equ c 1 and Equ c 2: A Comparison among Breeds

INTRODUCTION

Horse allergens are less studied than allergens from other furry animals and these allergens must be evaluated to understand the complexity of allergy to horses. The aims of this study were to develop assays for the horse allergens Equ c 1 and Equ c 2 in dander and saliva and to determine their levels in ten horse breeds. The study also included a comparison of these findings with previous results on the levels of Equ c 4 performed on the same study population.

METHOD

The study population included 170 horses from 10 horse breeds including American Curly and Russian Bashkir horse, which have been suggested to be hypoallergenic. Competitive ELISA assays were developed, with polyclonal antibodies as capture antibodies, for the detection of Equ c 1 and Equ c 2 in dander and saliva samples.

RESULTS

The horse allergens Equ c 1 and Equ c 2 were found in all dander and saliva samples from the ten horse breeds. The GM level (ng/µg protein) of Equ c 1 in dander was 470 (range 129-2,569) and in saliva samples, 40 (range 6-160). The GM level of Equ c 2 in dander was 138 (range 18-1,650) and in saliva samples, 0.8 (range 0.03-17). In dander, there were no significant differences in Equ c 1 and Equ c 2 GM levels between stallions, mares, and geldings.

CONCLUSION

Our results show high intra- and inter-breed variability. Neither the American Curly horse nor the Russian Bashkir horse, earlier categorized as hypoallergenic breeds, was associated with lower allergen levels of Equ c 1, Equ c 2, or Equ c 4 than the other horse breeds investigated.

Component-resolved diagnostics in pet allergy: Current perspectives and future directions

Furry mammals kept as pets are important allergen sources. The prevalence of sensitization to dander from various animals appears to be increasing worldwide. Several mammalian allergens from diverse species and distinct protein families have been characterized, and some are available for component-resolved diagnostics (CRD). This review presents an overview of mammalian aeroallergens, with a focus on cat, dog, and horse allergens. The potential of CRD in fine-tuning the diagnostic workup following traditional methods based on whole- allergen extracts and allergen immunotherapy is discussed. The review highlights the clinical utility of CRD, particularly as a marker/predictor of increased asthma risk and disease severity. Finally, several perspectives of the future implications of CRD are offered in the context of furry animal allergens.

Developments allergy in 2019 through the eyes of clinical and experimental allergy, part I mechanisms

In the first of two linked articles, we describe the development in the mechanisms underlying allergy as described by Clinical & Experimental Allergy and other journals in 2019. Experimental models of allergic disease, basic mechanisms, clinical mechanisms and allergens are all covered.

Levels of horse allergen Equ c 4 in dander and saliva from ten horse breeds

Background

Horses are an important source of allergens, but the distribution of horse allergens is poorly understood. Five horse allergens have been identified, Equ c 1‐4 and 6. Equ c 4 seems to be an important allergen, with an IgE‐binding frequency of 77% in horse‐sensitized individuals.

Objectives

The aim of this study was to investigate levels of horse allergen Equ c 4 in dander, saliva and urine from ten horse breeds.

Method

The study population included 170 horses (87 mares, 27 stallions, 56 geldings) from ten breeds. Horse dander, saliva and urine samples were collected. Levels of horse allergen Equ c 4 were quantified using a two‐site sandwich ELISA (mAb 103 and 14G4) and were expressed as Equ c 4 U/μg protein.

Results

The horse allergen Equ c 4 was present in all dander and saliva samples from ten horse breeds, with high within‐breed and inter‐breed variations; GM values were 639 Equ c 4 U/μg protein (range 5‐15 264) for dander and 39.5 (4‐263) for saliva. Equ c 4 was found in 19/21 urine samples. Adjusted for age, sex and changes over time, no differences between breeds could be seen in dander, while in saliva the North Swedish horse showed lower levels of Equ c 4 than any other breed. The levels of Equ c 4 protein in dander and saliva were significantly higher in samples from stallions compared to mares and geldings, independent of breed.

Conclusions and Clinical Relevance

The results show a high variability in allergen levels of Equ c 4 in dander and saliva both within and between breeds. Significantly higher levels were found in stallions compared to mares and geldings, independent of breed. Results suggest that none of the horse breeds studied can be recommended for individuals allergic to Equ c 4.