Diagnostic criteria for monoclonal B-cell lymphocytosis

Gerald E. Marti, Andy C. Rawstron, Paolo Ghia, Peter Hillmen, Richard S. Houlston, Neil Kay, Thérèse A. Schleinitz, Neil Caporaso

Research output: Contribution to journalReview articlepeer-review

307 Scopus citations


Very low levels of circulating monoclonal B-cell subpopulations can now be detected in apparently healthy individuals using flow cytometry. We propose the term 'monoclonal B-cell lymphocytosis' (MBL) to describe this finding. The aim of this document is to provide a working definition of MBL for future clinical, epidemiological and laboratory studies. We propose that the detection of a monoclonal B-cell population by light chain restriction is sufficient to define this condition in individuals not meeting the diagnostic criteria for other B-lymphoproliferative disorders. The majority of individuals with MBL will have cells that are indistinguishable from chronic lymphocytic leukaemia (CLL). However, this blood cell clonal expansion of CD5+ or CD5- B-lymphocytes is age-dependent and immunophenotypic heterogeneity is common. Longitudinal studies are required to determine whether MBL is a precursor state to CLL or other B-lymphoproliferative disease in a situation analogous to a monoclonal gammopathy of undetermined significance and myeloma. Future studies of MBL should be directed towards determining its relationship to clinical disease, particularly in individuals from families with a genetic predisposition to developing CLL.

Original languageEnglish (US)
Pages (from-to)325-332
Number of pages8
JournalBritish journal of haematology
Issue number3
StatePublished - Aug 2005


  • B cells
  • Early detection
  • Familial chronic lymphocytic leukaemia
  • Monoclonal B-cell lymphocytosis
  • Surrogate biomarker

ASJC Scopus subject areas

  • Hematology


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