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Neuman H, Arrouasse J, Benjamini O, Mehr R, Kedmi M. B cell M-CLL clones retain selection against replacement mutations in their immunoglobulin gene framework regions. Front Oncol 2023; 13:1115361. [PMID: 37007112 PMCID: PMC10060519 DOI: 10.3389/fonc.2023.1115361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Accepted: 03/03/2023] [Indexed: 03/18/2023] Open
Abstract
IntroductionChronic lymphocytic leukemia (CLL) is the most common adult leukemia, accounting for 30–40% of all adult leukemias. The dynamics of B-lymphocyte CLL clones with mutated immunoglobulin heavy chain variable region (IgHV) genes in their tumor (M-CLL) can be studied using mutational lineage trees.MethodsHere, we used lineage tree-based analyses of somatic hypermutation (SHM) and selection in M-CLL clones, comparing the dominant (presumably malignant) clones of 15 CLL patients to their non-dominant (presumably normal) B cell clones, and to those of healthy control repertoires. This type of analysis, which was never previously published in CLL, yielded the following novel insights. ResultsCLL dominant clones undergo – or retain – more replacement mutations that alter amino acid properties such as charge or hydropathy. Although, as expected, CLL dominant clones undergo weaker selection for replacement mutations in the complementarity determining regions (CDRs) and against replacement mutations in the framework regions (FWRs) than non-dominant clones in the same patients or normal B cell clones in healthy controls, they surprisingly retain some of the latter selection in their FWRs. Finally, using machine learning, we show that even the non-dominant clones in CLL patients differ from healthy control clones in various features, most notably their expression of higher fractions of transition mutations. DiscussionOverall, CLL seems to be characterized by significant loosening – but not a complete loss – of the selection forces operating on B cell clones, and possibly also by changes in SHM mechanisms.
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Affiliation(s)
- Hadas Neuman
- The Mina and Everard Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel
| | - Jessica Arrouasse
- The Mina and Everard Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel
| | - Ohad Benjamini
- Division of Hematology and Bone Marrow Transplantation, Chaim Sheba Medical Center, Ramat-Gan, Israel
- Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Ramit Mehr
- The Mina and Everard Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel
- *Correspondence: Ramit Mehr,
| | - Meirav Kedmi
- The Mina and Everard Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel
- Division of Hematology and Bone Marrow Transplantation, Chaim Sheba Medical Center, Ramat-Gan, Israel
- Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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Iosselevitch I, Tabibian-Keissar H, Barshack I, Mehr R. Gastric DLBCL clonal evolution as function of patient age. Front Immunol 2022; 13:957170. [PMID: 36105806 PMCID: PMC9464916 DOI: 10.3389/fimmu.2022.957170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/01/2022] [Indexed: 01/10/2023] Open
Abstract
Diffuse large B cell lymphoma (DLBCL) is the most common type of NHL, accounting for about 40% of NHL cases, and is one of the most aggressive lymphomas. DLBCL is widespread in individuals aged more than 50 years old, with a maximum incidence in the seventh decade, but it may also occur in younger patients. DLBCL may occur in any immune system tissue, including those around the gastrointestinal tract, and even in the stomach, though gastric DLBCL has yet to be sufficiently investigated. This study aimed to understand changes in gastric Diffuse Large B cell lymphoma (gastric DLBCL) development with age. Immunoglobulin (Ig) heavy chain variable region genes were amplified from sections of nine preserved biopsies, from patients whose age varied between 25 and 89 years, sequenced and analyzed. We show first that identification of the malignant clone based on the biopsies is much less certain than was previously assumed; and second that, contrary to expectations, the repertoire of gastric B cell clones is more diverse among the elderly DLBCL patients than among the young.
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Affiliation(s)
- Irina Iosselevitch
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | | | - Iris Barshack
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
- Department of Pathology, Sheba Medical Center, Ramat-Gan, Israel
- Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Ramit Mehr
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
- *Correspondence: Ramit Mehr,
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