Omalizumab reduced viable human B cell numbers. Total B cells (A) and naïve and memory B cell subsets (B) were left non-treated (NT) or treated with IL-4 + anti-CD40 in the presence or absence of 1 μg/mL omalizumab (Om) or human IgG. Live cells were enumerated by trypan blue exclusion 3 days later. Data are expressed as the mean ± SEM (n = 7 tonsils, panel A; n = 4 tonsils, panel B). Statistically significant differences (p values) were determined by t-test.