Ectopic expression of ILT3 is specific for peripheral blood CLL cells and CLL progenitors in the bone marrow. (A) Flow cytometric analysis of surface ILT3 expression on representative samples of CD19⁺ healthy and CLL B cells. (B) Flow cytometric analysis of surface ILT3 expression on B cells from healthy donors, patients with nonlymphoproliferative diseases (NLD), and CLL patients grouped by age. (C) Gating strategy of multicolor flow cytometric analysis to distinguish neoplastic and normal B cells in the same representative CLL patient. (D) Quantification of ILT3 surface expression in healthy and malignant B cells from 4 CLL patients. (E) Gating strategy for flow cytometric analysis to identify HSCs among mononuclear cells isolated from the bone marrow of representative patients. (F) Quantification of surface ILT3 expression on bone marrow HSCs isolated from 3 CLL patients and 3 patients with NHL. Shown are mean values ± SEM. **P < .01; ***P < .001.