Allergen-specific T cell quantity in blood is higher in allergic compared to nonallergic individuals

Background: Allergen-specific IgE production is a hallmark of allergic asthma/rhinitis/eczema. Theoretically this could be due to a high number of allergen-specific B cells or allergen-specific T cells helping allergen-specific B cells differentiate into IgE-producing plasma cells. Here, we determined whether the number of allergen-specific B cells or T helper (Th) cells is higher in allergic individuals compared to nonallergic individuals. Methods: A total of 52 allergic individuals and 32 nonallergic individuals were studied. The allergen-specific B and Th cells were enumerated by culturing CFSE-loaded blood mononuclear cells for 7-days with allergen (cat, Timothy or birch), and determining the number of proliferating B or Th cells (diluting CFSE) by flow cytometry. Allergenspecific IgE concentration was determined by fluorescent enzymoimmunoassay (FEIA). Results: The quantities of proliferating Th cells but not proliferating B cells specific for cat, Timothy and birch were significantly higher in cat-, Timothy-and birch-allergic individuals compared to nonallergic individuals. The titer of allergen-specific IgE showed significant correlation with allergen-specific Th cells and not with allergen-specific B cells for all 3 allergens. Conclusions: A high number of allergen-specific proliferating Th cells, but not proliferating B cells, may play a role in the pathogenesis of allergic asthma/rhinitis/eczema.