Effects of dasatinib on histamine release in human basophils. (A) Basophils from 14 healthy donors were incubated with control medium (control) or dasatinib (1 μM) at 37°C for 30 minutes. Then, cells were washed and exposed to an anti-IgE antibody (1 μg/mL) for 30 minutes. Thereafter, cells were centrifuged and the cell-free supernatants and lysates examined for histamine content by RIA. Results show the percentage of histamine release. The inhibitory effect of dasatinib on histamine release was significant (P < .05). (B) Basophils were preincubated in control medium (■-■) or dasatinib, 1 μM (●-●) for 30 minutes. Thereafter, basophils were washed and incubated in various concentrations of anti-IgE (37°C, 5% CO₂) for 30 minutes. Then, cells were centrifuged at 4°C and the cell-free supernatants and lysates examined for the amounts of histamine. Results show the percentage of released histamine and represent the mean (± SD) from triplicates. (C) Normal basophils were incubated in control buffer (■-■), or in buffer with IL-3 (100 ng/mL) in the absence (▲-▲) or presence (♦-♦) of dasatinib (1 μM) for 30 minutes (37°C). Thereafter, cells were washed and incubated in various concentrations of anti-IgE (37°C, 30 minutes). Then, cells were centrifuged and histamine levels measured in cell-free supernatants and cell lysates. Results show the percentage of released histamine and represent mean (± SD) values from triplicates in one donor. (D-E) Dose-dependent effects of dasatinib on anti-IgE–induced release of histamine from normal basophils (D) and CML basophils (E). Basophils were preincubated in control medium or in various concentrations of dasatinib (as indicated) for 30 minutes at 37°C. Then, cells were washed and incubated with anti-IgE (1 μg/mL) for 30 minutes. After centrifugation at 4°C, cell-free supernatants and lysates were analyzed for the con-tent of histamine. Results show the percentages of released histamine and represent the means (± SD) from triplicates.