Mugwort-Sensitized Individuals from North Europe, South Europe and North America Show Different IgE Reactivity Patterns

BACKGROUND: Sensitization to weed pollen allergens at the molecular level is not fully understood. We studied IgE reactivity to the major mugwort allergen Art v 1 in relation to allergens from other weed pollen and cross-reactive components in mugwort-sensitized subjects. METHODS: Art v 1 and Amb a 1 were affinity purified and coupled to experimental ImmunoCAP® tests. Samples from North Europe (n = 50), South Europe (n = 19) and North America (n = 41) were analyzed for IgE against mugwort pollen, weed allergen components, pan-allergens and cross-reactive carbohydrate determinants (CCDs). RESULTS: The prevalence of IgE reactivity (>0.35 kU(A)/l) to Art v 1 was significantly higher in samples from North Europe than in those from North America. IgE to Amb a 1 was more common in North America than in North and South Europe, while IgE to Par j 2 was common in South Europe, less common in North America, and absent in North Europe. IgE to Art v 3 in mugwort-allergic patients was more common in North Europe than in South Europe and North America, while IgE to Sal k 1 was similar between the areas. Subjects with an Art v 1/mugwort-specific IgE ratio <0.5 had more often IgE to Amb a 1, profilin, polcalcin and CCDs than subjects with a ratio >0.5. CONCLUSIONS: Mugwort-sensitized subjects have different IgE reactivity profiles to weed allergens, reflecting their exposure to various pollens. Subjects with a low ratio between the IgE levels to Art v 1 and mugwort have a diverse IgE reactivity profile, indicating a role for cross-reactive allergens in their mugwort sensitization.