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Updated: Sep 4, 2025
Immunoglobulin Gene Sequence Analysis In Chronic Lymphocytic Leukemia: From Patient Material To Sequence Interpretation
Published on: November 26, 2018
Characterizing Features of Human Circulating B Cells Carrying CLL-Like Stereotyped Immunoglobulin Rearrangements
Davide Bagnara1, Monica Colombo2, Daniele Reverberi2
1Department of Experimental Medicine, University of Genoa, Genoa, Italy.
Insights
Chronic Lymphocytic Leukemia (CLL) stereotyped B cell receptors, or BCRs, are not exclusive to malignant cells. Our study found CLL-like BCRs in healthy donors, suggesting immune-genotype details can define the CLL cell of origin.
Area of Science:
- Immunology
- Hematology
- Genetics
Background:
- Chronic Lymphocytic Leukemia (CLL) involves abnormal CD5+ B cell accumulation with low surface immunoglobulins (IG).
- Approximately 40% of CLL cases feature quasi-identical B cell receptors (BCRs), termed stereotyped BCRs.
- CLL-like stereotyped IG rearrangements are also found in normal B cells within the public IG repertoire.
Purpose of the Study:
- To investigate the representation and characteristics of CLL-like stereotyped IG rearrangements in healthy donor B cell subpopulations.
- To determine if CLL-like stereotyped IG rearrangements are enriched in specific B cell subsets, particularly CD5+ cells.
- To compare the features of CLL-like stereotyped IG with those of CLL stereotyped IG to understand their ontogeny.
Main Methods:
- Purification of B cell subpopulations from peripheral blood of nine healthy donors.
- Fractionation of B cells based on CD5 expression and IG light chain (IGκ, IGλ) type.
- High-throughput sequencing of IG rearrangements to identify and analyze CLL-like stereotyped IG.
Main Results:
- CLL-like stereotyped IG rearrangements were not preferentially accumulated in CD5+ B cells or specific B cell subpopulations.
- The distribution of CLL-like stereotyped IG was not restricted to a single IG light chain type.
- While sharing IGHV mutational status with CLL stereotyped rearrangements, CLL-like stereotyped IG exhibited subset-specific behaviors in IGHV gene usage and frequency.
Conclusions:
- Immuno-phenotype does not fully explain the presence of CLL-like stereotyped IG in healthy individuals.
- The features of the CLL stereotyped IG repertoire suggest a stereotyped subset-specific ontogeny, distinct from immuno-phenotypic observations.
- Immune-genotype analysis offers crucial insights for tracking and defining the cell of origin in CLL.
Abstract:
Chronic Lymphocytic Leukemia (CLL) is characterized by the accumulation of monoclonal CD5+ B cells with low surface immunoglobulins (IG). About 40% of CLL clones utilize quasi-identical B cell receptors, defined as stereotyped BCR. CLL-like stereotyped-IG rearrangements are present in normal B cells as a part of the public IG repertoire. In this study, we collected details on the representation and features of CLL-like stereotyped-IG in the IGH repertoire of B-cell subpopulations purified from the peripheral blood of nine healthy donors. The B-cell subpopulations were also fractioned according to the expression of surface CD5 molecules and IG light chain, IGκ and IGλ. IG rearrangements, obtained by high throughput sequencing, were scanned for the presence of CLL-like stereotyped-IG. CLL-like stereotyped-IG did not accumulate preferentially in the CD5+ B cells, nor in specific B-cell subpopulations or the CD5+ cell fraction thereof, and their distribution was not restricted to a single IG light chain type. CLL-like stereotyped-IG shared with the corresponding CLL stereotype rearrangements the IGHV mutational status. Instead, for other features such as IGHV genes and frequency, CLL stereotyped-IGs presented a CLL-like subset specific behavior which could, or could not, be consistent with CLL stereotyped-IGs. Therefore, as opposed to the immuno-phenotype, the features of the CLL stereotyped-IG repertoire suggest a CLL stereotyped subset-specific ontogeny. Overall, these findings suggest that the immune-genotype can provide essential details in tracking and defining the CLL cell of origin.
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