Detection of HDC and histamine levels in Ba/F3 cells inducibly expressing the BCR/ABL oncoprotein. (A-B) RT-PCR analysis of HDC mRNA expression in Ton.B210 cells (A) and Ton.B210-X cells (B) cultured in the absence of IL-3 (Control), in the presence of IL-3, or in the presence of doxycycline (1 μg/mL) to induce BCR/ABL for 24 hours. RT-PCR was performed using primers specific for HDC or β-actin (loading control). (C-D) Histamine levels in lysates of Ton.B210 cells (C) and Ton.B210-X cells (D) cultured in the absence of IL-3 (Control), in the presence of IL-3, or in the presence of doxycycline (1 μg/mL) to express BCR/ABL for 24 hours. Histamine was quantified by RIA. Results represent the mean ± SD from 3 independent experiments. ^*P < .05. (E) RT-PCR analysis of HDC mRNA expression in Ton.B210-X cells cultured in the absence of IL-3 (Control), in the presence of IL-3, or in the presence of doxycycline (BCR/ABL) for 24 hours. BCR/ABL-expressing cells were incubated with control medium, imatinib, 1 μM (BCR/ABL + STI571), or AMN107, 100 nM (BCR/ABL + AMN107) for another 24 hours. RT-PCR was performed using primers specific for HDC or β-actin (loading control). The RT omission control (-RT) is also shown. (F) Histamine levels (by RIA) in Ton.B210-X cells cultured in the absence of IL-3 (Control) or in the presence of doxycycline with or without inhibitory drugs (STI571, 1 μM; AMN107, 100 nM) for 24 hours. Results represent the mean ± SD from 3 independent experiments. ^*P < .05.