Characterization of the Intraclonal Complexity of Chronic Lymphocytic Leukemia B Cells: Potential Influences of B-Cell Receptor Crosstalk with Other Stimuli

Chronic lymphocytic leukemia (CLL) clones contain subpopulations differing in time since the last cell division (“age”): recently born, proliferative (PF; CXCR4DimCD5Bright), intermediate (IF; CXCR4IntCD5Int), and resting (RF; CXCR4BrightCD5Dim) fractions. Herein, we used deuterium (2H) incorporation into newly synthesized DNA patients to refine kinetics of CLL by characterizing two additional CXCR4/CD5 fractions, i.e., double dim (DDF; CXCR4DimCD5Dim) bright (DBF; CXCR4BrightCD5Bright); intraclonal fractions surface membrane (sm) IgM IgD densities. Although DDF was enriched divided cells DBF older cells, PF RF remained most youngest oldest respectively. Similarly, smIgMHigh smIgDHigh were youngest, smIgMLow smIgDLow oldest, when using smIG levels as discriminator. Surprisingly, closest stimulatory event bore high smIG, stimulating via TLR9 yielded a phenotype more consistent with vivo setting. Finally, less sensitive inhibition ibrutinib. Collectively, these data define divergent ages phenotypes suggest that BCR engagement alone is not responsible for found vivo, differential sensitivity distinct ibrutinib might account, part, therapeutic relapse.