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Updated: Aug 11, 2026
Flow Cytometry to Estimate Leukemia Stem Cells in Primary Acute Myeloid Leukemia and in Patient-derived-xenografts, at Diagnosis and Follow Up
Published on: March 26, 2018
Rapid detection of phosphotyrosine proteins by flow cytometric analysis in Bcr-Abl-positive cells
Vanessa Desplat1, Valérie Lagarde, Francis Belloc
1Laboratoire Hématopoïèse Normale et Pathologique, FRE CNRS 2617, Université Victor Ségalen, rue Léo-Saignat, 33076 Bordeaux Cedex, France.
Background:
Constitutive tyrosine phosphorylation derived from Bcr-Abl kinase activity is the major characteristic of Bcr-Abl positive cells. In this study, we developed a method to detect the phosphotyrosine proteins by flow cytometry and we asked whether phosphorylation was affected by imatinib mesylate treatment.
Methods:
Cells were treated or not with imatinib mesylate, fixed and permeabilized by PFA followed by saponin, then stained with anti-phosphotyrosine (p-tyr) monoclonal antibody and analyzed by flow cytometry.
Results:
Optimal staining parameters were performed with p-tyr antibody using K562 and LAMA84 lines that displayed high levels of tyrosine phosphorylation as compared to the control line, HL60. Tyrosine phosphorylation was inhibited by imatinib in a dose-dependent manner, but not modified by other inhibitors demonstrating that the staining detected is specific to Bcr-Abl phosphorylation. The staining of imatinib-resistant cell lines such as the mutated BaF/Bcr-AblT315I cell line or resistant CML patient cells, showed that hyperphosphorylation was not affected by imatinib treatment. In one CML patient, our technique permitted us to detect a small hyperphosphorylated population resistant to imatinib that appeared hyperphosphorylated and amplified at the time of relapse.
Conclusions:
We have developed a flow cytometric technique presenting several advantages such as rapidity and sensitivity, which requires fewer cells than the Western blot.
