Identification of three subgroups of B cell chronic lymphocytic leukemia based upon mutations of BCL-6 and IgV genes

Leukemia. 2000 May;14(5):811-5. doi: 10.1038/sj.leu.2401766.

Abstract

Although B cell chronic lymphocytic leukemia (B-CLL) has been traditionally viewed as a tumor of virgin B cells, this notion has been recently questioned by data suggesting that a fraction of B-CLL derives from antigen experienced B cells. In order to further clarify the histogenetic derivation of this lymphoproliferation, we have analyzed the DNA sequences of the 5' non-coding region of BCL-6 proto-oncogene in 28 cases of B-CLL. Mutations of BCL-6 proto-oncogene, a zinc finger transcription factor implicated in lymphoma development, represent a histogenetic marker of B cell transit through the germinal center (GC) and occur frequently in B cell malignancies derived from GC or post-GC B cells. For comparison, the same tumor panel was analyzed for somatic mutations of the rearranged immunoglobulin variable (IgV) genes, which are known to be acquired at the time of B cell transit through the GC. Sequence analyses of BCL-6 and IgV genes allowed the definition of three groups of B-CLL. Group I B-CLL displayed mutations of both BCL-6 and IgV genes (10/28; 36%). Group II B-CLL displayed mutated IgV genes, but a germline BCL-6 gene (5/28; 18%). Finally, group III B-CLL included the remaining cases (13/28; 46%) that were characterized by the absence of somatic mutations of both BCL-6 and IgV genes. Overall, the distribution of BCL-6 and IgV mutations in B-CLL reinforce the notion that this leukemia is histogenetically heterogeneous and that a substantial subgroup of these lymphoproliferations derives from post-germinal center B cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • DNA-Binding Proteins / genetics*
  • Gene Rearrangement, B-Lymphocyte
  • Genes, Immunoglobulin
  • Humans
  • Immunoglobulin Heavy Chains / genetics
  • Immunoglobulin Light Chains / genetics
  • Immunoglobulin Variable Region / genetics*
  • Leukemia, Lymphocytic, Chronic, B-Cell / classification*
  • Leukemia, Lymphocytic, Chronic, B-Cell / genetics*
  • Leukemia, Lymphocytic, Chronic, B-Cell / immunology
  • Mutation*
  • Point Mutation
  • Proto-Oncogene Mas
  • Proto-Oncogene Proteins / genetics*
  • Proto-Oncogene Proteins c-bcl-6
  • Proto-Oncogenes
  • Transcription Factors / genetics*
  • Tumor Cells, Cultured
  • Zinc Fingers

Substances

  • DNA-Binding Proteins
  • Immunoglobulin Heavy Chains
  • Immunoglobulin Light Chains
  • Immunoglobulin Variable Region
  • MAS1 protein, human
  • Proto-Oncogene Mas
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-6
  • Transcription Factors