Comparison of house dust mite sensitization profiles in allergic adults from Canada, Europe, South Africa and USA

Abstract

Background Sensitization to house dust mite (HDM) is a leading cause of allergic rhinitis and asthma. Despite more than 30 HDM‐derived allergens having been identified to date, specific therapeutic approaches do not yet take into account the local sensitization profiles of patients. This study aimed to identify patterns of HDM sensitization in HDM‐allergic adults living in distinct geographic areas, to inform the development of targeted diagnostic and therapeutic tools. Methods Serum samples from 685 HDM‐allergic subjects from Canada, Europe, South Africa, and the USA were tested for levels of IgE specific for 17 micro‐arrayed HDM allergens by ImmunoCAP Immuno Solid‐phase Allergen Chip (ISAC) technology. Results The results confirmed significant geographical variability in sensitization patterns and levels of IgE. In all areas, the major sensitizers were the group 1 and group 2 allergens and Der p 23. Der p 23 was a frequent sensitizer: 64% of the subjects had IgE specific for Der p 23, and 2.3% were monosensitized to it. In South Africa, Der p 23 was the dominant HDM allergen (86% prevalence) and Der p 7 achieved major allergen status (56%). IgE sensitization to HDM was influenced by asthmatic status, levels of allergen exposure, age, race‐ethnicity and smoking status, but not by BMI. Conclusion Sensitization profiles to HDM allergens differ considerably among distinct geographic areas, with Der p 7 and Der p 23 being major sensitizers in South Africa. Such heterogeneity should be taken into account in the diagnosis and treatment of HDM‐allergic patients.

IgE Epitopes of the House Dust Mite Allergen Der p 7 Are Mainly Discontinuous and Conformational

“…Two recent studies provided evidence that HDM allergen extract-based AIT vaccines provide mainly protection against Der p 1 and Der p 2 whereas they induce low or no IgG antibody responses to Der p 5, Der p 7, Der p 21, and Der p 23, and treatment success is lower in patients who are sensitized against the latter allergens as compared to patients who are mainly sensitized to Der p 1 and/or Der p 2 ( 17 , 18 ). Der p 7 has been defined as a mid-tier house dust mite allergen recognized by more than 30% of HDM sensitized patients ( 3 ) but it has been shown that it can be a major HDM allergen recognized by more than 50% of HDM allergic patients in certain populations ( 5 , 9 ). However, not only the frequency of IgE recognition defines if an allergen is important but also its clinical relevance which may be measured by determining its allergenic activity in vitro and in vivo needs to be taken into consideration as has been suggested recently ( 36 , 37 ).…”

“…Originally, Der p 7 was categorized as mid-tier group of mite allergens with a frequency of IgE binding 17% to 52% depending on the tested population ( 4 – 8 ). A very recent study reported an IgE prevalence of 56% for Der p 7 in a South African population, and accordingly, Der p 7 was the second most common sensitizing allergen after Der p 23 in this population ( 9 ). The clinical relevance of Der p 7 was emphasized already in the study by Lynch et al.…”

“…Originally, Der p 7 was categorized as mid-tier group of mite allergens with a frequency of IgE binding 17% to 52% depending on the tested population (4)(5)(6)(7)(8). A very recent study reported an IgE prevalence of 56% for Der p 7 in a South African population, and accordingly, Der p 7 was the second most common sensitizing allergen after Der p 23 in this population (9). The clinical relevance of Der p 7 was emphasized already in the study by Lynch et al who reported that Der p 7 induced immediate hypersensitivity skin-test reactions in 52% of patients who were positive to HDM extract implicating its strong allergenic activity and Der p 7 accounted for binding of one fifth of HDM-specific IgE levels (10).…”

Environmental exposure of Der p 23 in household dust samples

“…Previous studies have demonstrated that the capacity of Der p 23 to exacerbate mite allergic symptoms is very high, and this does not correlate with its abundance 1–3,5 . However, its sensitisation has been related to asthma, mainly in children 4 .…”

“…In recent years, Der p 23, a peritrophin‐like protein that is mainly present in the posterior midgut and the outer membrane of mite faeces, has also been identified as a potent allergen, despite its low concentrations 1,2 . Previous studies have demonstrated that Der p 23 elicits a positive sensitisation rate of 75% in patients with house dust mite (HDM) allergies, particularly in children with persistent moderate‐to‐severe asthma 2–5 . Different studies have investigated the correlation between the levels of HDM allergen exposure and risk of developing allergic sensitisation and, consequently, allergic symptoms 3,6 .…”