Omalizumab reduced the number of membrane IgE+ B cells. B cells were left non-treated (NT) or treated with IL-4 + anti-CD40 in the presence or absence of 1 μg/mL omalizumab (Om). After 4 days B cells were stained with PE-conjugated anti-human IgE. (A) Number of mIgE+ cells. (B) Mean fluorescence intensity. Data are expressed as the mean ± SEM (n = 6 tonsils). Statistically significant difference (p value) was determined by t-test.