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Chronic lymphocytic leukaemia: one disease or two?
1Department of Haematology and Oncology, Royal Bournemouth Hospital, Castle Lane East, Bournemouth BH7 7DW, UK. terjoha@aol.com
Annals of Hematology
|July 11, 2002
Summary
Chronic lymphocytic leukemia (CLL) may be two distinct diseases, not one. Somatic mutations in immunoglobulin genes separate CLL into benign and malignant forms with different prognoses, suggesting distinct origins despite shared B-cell defects.
Area of Science:
- Hematology
- Oncology
- Immunology
Background:
- The presence or absence of somatic mutations in immunoglobulin variable region genes differentiates chronic lymphocytic leukemia (CLL) into distinct clinical subsets.
- This genetic distinction raises questions about whether CLL represents a single disease entity or two separate conditions.
- Despite similarities in morphology, immunophenotype, and gene expression, the divergent natural histories of these subsets suggest distinct pathological processes.
Purpose of the Study:
- To investigate the hypothesis that chronic lymphocytic leukemia (CLL) comprises two distinct diseases based on somatic mutation status.
- To explore the underlying B-lymphocyte defect and its role in differentiating CLL subsets.
- To understand how B-cell receptor stimulation influences disease presentation and progression in CLL.
Main Methods:
- Analysis of somatic mutations in immunoglobulin variable region genes in CLL patient cohorts.
- Comparison of morphological, immunophenotypic, and gene expression profiles between mutated and unmutated CLL subsets.
- Evaluation of B-cell receptor signaling pathways and their role in disease pathogenesis.
Main Results:
- Somatic mutation status in immunoglobulin variable region genes clearly separates CLL into subsets with significantly different clinical outcomes.
- A common intrinsic defect in B-lymphocytes is proposed, leading to a specific response pattern (partial activation, anergy, anti-apoptosis) upon B-cell receptor stimulation.
- Differences in disease progression and characteristics, including CD38 expression and chromosomal abnormalities, are linked to the mode and extent of B-cell receptor stimulation.
Conclusions:
- Chronic lymphocytic leukemia (CLL) likely represents two distinct diseases, differentiated by somatic mutation status and exhibiting divergent natural histories.
- The type of B-cell receptor stimulation (conventional vs. unconventional) dictates the clinical presentation and progression of CLL.
- Further B-cell receptor stimulation contributes to secondary differences observed in some CLL subsets, such as proliferation and specific genetic alterations.