Allergen-Specific B Cell Quantity Is Similar in Allergic and Nonallergic Individuals, Whereas Allergen-Specific T Cells May Be Increased in Allergic Individuals

Allergen-specific IgE production is a hallmark of allergic asthma, rhinitis or eczema. Theoretically this could be due to a high number of allergen-specific B cells, a high number of allergen-specific T cells helping allergen-specific B cells to differentiate into IgE plasma cells, or other mechanisms. In this study, we compared the number of allergenspecific B cells and T helper (Th) cells in 41 patients with allergic asthma/rhinitis/eczema (allergic individuals) and 34 nonallergic individuals. Allergen-specific B and Th cells were enumerated by culturing CFSE-loaded blood mononuclear cells for 7 days with allergen (cat, dog, D.pteronyssimus, Timothy or birch), and determining by flow cytometry the number of B or Th cells that had proliferated (diluted CFSE). The quantities of B cells specific for each of the 5 allergens were similar in individuals allergic to the allergen (per skin prick test result) compared to nonallergic individuals. The quantity of Timothy-specific Th cells was 3-times higher in Timothy-allergic individuals compared to nonallergic individuals (p=0.023). In contrast, the quantity of cat-specific Th cells was similar in cat-allergic and nonallergic individuals. The quantities of dog, D.pteronyssimus and birch-specific Th cells were slightly higher in dog, D.pteronyssiumus and birch-allergic compared to nonallergic individuals. No significant change in the number of allergen specific B and Th cells was found when blood drawn from the same individual at different time points was compared for 3 allergic and 3 non-allergic individuals. We conclude that for some allergens (eg, Timothy), a high number of allergen-specific Th cells, but not B cells, may play a role in the pathogenesis of allergic asthma/rhinitis/eczema. For other allergens (eg, cat), the pathogenesis may be different.