Effect of anti-IgE therapy on allergen specific T cell proliferation. (A) Allergen specific CD4 T cell proliferation was measured by calculating the percentage of CFSElow cells and the results compared both at baseline and at completion of a 16-week trial of omalizumab. (B) Example of an allergen dose response to peanut Ag for subject 2, performed at baseline (circles) and at study completion (squares). (C) The EC50 for allergen proliferation was compared at baseline and at study completion. (D) The precursor frequency of allergen specific T cells was determined by CFSE dye dilution and compared at baseline and at study completion. Each color/symbol combination represents one subject and one allergen; results in A and D include two allergens examined for each subject.