Analysis of the multicomponent ALEX array data to examine patterns of sensitization in Cape Town, South Africa.

Introduction: This study analysed allergen sensitization patterns in Cape Town, a biodiversity-rich region with a Mediterranean climate, using ALEX® and ALEX²® multiplex component-resolved diagnostics tools. It aimed to address gaps in allergen sensitisation pattern data and complement aerobiological monitoring.

Methods and results: A retrospective review of 708 adults and children attending two tertiary allergy clinics (2019-2024) found that house dust mites were the most common allergens, affecting 50%-60% of participants, with Der p 23 particularly prevalent (53%). Grass pollen sensitization was also high (46%), with 85% sensitised to the C4 grass Bermuda. Tree pollen sensitisation occurred in 29% with 14% sensitised to a diverse range of trees but neither London plane nor Cypress currently recommended in limited testing panels. Common food allergens included fruits (30%), seafood (27%), and nuts (25%), often linked to pollen cross-reactivity.

Conclusion: Our study confirms a known pattern of aeroallergen sensitisation for a coastal temperate region, with increasing pollen sensitisation, particular C4 grasses. Clinicians should be aware of the diversity of tree pollen sensitisation, cross-reactivity patterns between food and pollen sensitisations and rates of minor allergen sensitisations for Blomia and animal danders when considering allergen-immunotherapies.