D3.222 - Monitoring the immune response during the first year of SCIT in Ragweed allergy

Allergen-specific immunotherapy (AIT) is the only disease-modifying treatment for IgE-mediated allergic diseases. Basophils play a key role in immediate hypersensitivity reactions, and the basophil activation test (BAT) is increasingly used as a functional biomarker to monitor immunological changes during AIT. However, data regarding basophil responsiveness during the first year of subcutaneous immunotherapy (SCIT) in ragweed allergy remain limited.

Ten patients with clinically confirmed ragweed allergy and positive skin prick tests were enrolled. Immunological assessment was performed prior to treatment initiation and after 12 months of subcutaneous immunotherapy (SCIT) using ragweed pollen extract.Basophil activation test (BAT) was performed using six different concentrations of allergen extract and the major allergen Amb a 1, by measuring CD63 expression as a marker of basophil degranulation. Additionally, serum specific IgE levels against total ragweed extract and Amb a 1 were quantified using the ImmunoCAP assay.

After one year of AIT, mean specific IgE levels to ragweed extract increased slightly from 56.1 kUA/L to 61.5 kUA/L. Similarly, IgE specific to Amb a 1 increased from 44.3 kU/L to 50.9 kU/L.

Despite this moderate rise in IgE levels, BAT analysis demonstrated a significant decrease in basophil degranulation, indicating a substantial reduction in post-treatment immunological reactivity.

One year of SCIT with ragweed pollen extract is associated with a marked reduction in basophil reactivity, reflecting a favorable immunomodulatory effect. The modest increase in specific IgE levels observed at this stage represents a known and expected immunological response during therapy.