Recognition of nonmalignant hematopoietic cells and chronic myeloid leukemia. Monocytes (CD14⁺), B cells (CD19⁺), and T cells (CD3⁺) were isolated from PBMCs from the patient obtained before alloSCT by flow cytometry. Isolated monocytes were cultured in vitro to immature and mature DCs. CD34⁺ chronic myeloid leukemia (CML) progenitor cells were isolated from bone marrow cells obtained from the patient after alloSCT during the relapse before treatment with DLI. In addition, CD34⁺ cells were isolated from other patients with CML and cultured in vitro to professional APCs. CD4⁺ T-cell clones were tested against (A) patient-derived monocytes, immature and mature DCs; (B) patient-derived T cells, B cells, and CD34⁺ CML progenitor cells; and (C) CD34⁺ CML progenitor cells from other patients with and without in vitro induced APC phenotype. Mean release of IFN-γ (ng/mL) in 50-μL supernatants of single (monocytes, immature DCs, mature DCs, patient-derived CD34⁺ CML progenitor cells) or duplicate wells is shown. nd indicates not determined