Coexpression of 97A6 antigen and IgE on PB and BM cells. Ficoll-Hypaque PB or BM cells were stained with MoAb 97A6-PE and anti-IgE-FITC and analyzed on a FACSCalibur flow cytometer. (A) Expression on Ficoll-Hypaque PB cells gated on “lymphocytes” (low side scatter cells). (B) Expression on MACS-selected 97A6⁺ PB cells. (C) Expression on PB cells selected with the StemSep basophil kit. (D) Expression on Ficoll-Hypaque BM cells. The gate in this plot indicates the sort window for morphological analysis of cells shown in Fig 1D. Plot (E) shows the display of a selected PB sample from a patient with CML in accelerated phase and plot (F) from a patient with CML in chronic phase. Note that the 97A6⁺IgE⁻ sample in E contains immature basophils (morphology shown in Fig 1C).