Dramatically decreased T cell responses but persistent IgE upon reduced pollen exposure

Area of Science:

• Immunology
• Allergology
• Environmental Health

Background:

• Mugwort pollen allergy is common in Europe, with Art v 1 as its primary allergen.
• Art v 1 contains a single T cell epitope, making mugwort allergy a suitable model for studying T cell responses.
• A significant decline in T cell responses to Art v 1 was observed post-2004.

Purpose of the Study:

• To investigate the correlation between local mugwort pollen exposure and allergen-specific T cell responses.
• To understand the long-term maintenance of specific IgE levels despite reduced allergen exposure.

Main Methods:

• Retrospective analysis of local mugwort pollen exposure data.
• Assessment of T cell responses to Art v 1 in mugwort-allergic individuals.
• Measurement of serum IgE antibodies specific for Art v 1.

Main Results:

• Total annual pollen indices significantly decreased after 2004 and did not recover.
• Local sensitization and serum IgE levels specific for Art v 1 remained stable until 2015.
• Reduced pollen exposure led to undetectable allergen-specific T cell responses.

Conclusions:

• Long-term reduction in natural allergen exposure can lead to a decline in T cell responses.
• Specific IgE levels can be maintained for extended periods even with minimal allergen exposure.
• Mugwort pollen allergy serves as a model to demonstrate the dissociation between IgE levels and T cell reactivity under reduced exposure conditions.