Diagnostic criteria for monoclonal B-cell lymphocytosis

Authors

  • Gerald E. Marti,

    1. Center for Biologics Evaluation and Research (CBER), US Food and Drug Administration (FDA), NIH, Bethesda, MD, USA
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  • Andy C. Rawstron,

    1. Haematological Malignancy Diagnostic Service, Leeds General Infirmary, Leeds Teaching Hospitals NHS Trust, Leeds, UK
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  • Paolo Ghia,

    1. Department of Oncological Sciences, University of Torino and Laboratory of Cancer Immunology, Istituto per la Ricerca e la Cura del Cancro, Candiolo (TO), Italy
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  • Peter Hillmen,

    1. Haematological Malignancy Diagnostic Service, Leeds General Infirmary, Leeds Teaching Hospitals NHS Trust, Leeds, UK
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  • Richard S. Houlston,

    1. Section of Cancer Genetics, Institute of Cancer Research, Sutton, Surrey, UK
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  • Neil Kay,

    1. Division of Hematology, Mayo Clinic, Rochester, MN, USA
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  • Thérèse A. Schleinitz,

    1. Center for Biologics Evaluation and Research (CBER), US Food and Drug Administration (FDA), NIH, Bethesda, MD, USA
    2. Institut Paoli-Calmettes, Marseille Cedex9, France
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  • Neil Caporaso,

    1. Department of Medicine, Division of Cancer Epidemiology and Genetics, Genetic Epidemiology Branch, National Cancer Institute, NIH, Bethesda, MD, USA
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  • The International Familial CLL Consortium

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    • *

      Other contributing members of the IFCLL: Pablo Bertin, Federico Caligaris-Cappio, Timothy Call, Daniel Catovsky, Finbarr Cotter, James Cerhan, Nicholas Chiorazzi, Guillaume Dighiero, Robin Foa, Lynn Goldin, Viggo Joensson, Michael Keating, Thomas Kipps, Francessca R. Mauro, Kanti Rai, Laura Rassenti, Sara Strom, Robert Vogt and Peter Wiernik.


Gerald E. Marti, MD, PhD, CMDR (PHS), Flow and Image Cytometry Section, LSCB DCGT OCTGT, CBER FDA NIH Bdg 29B Rm 2NN08, 8800 Rockville Pike, Bethesda, MD 20892, USA.
E-mail: gemarti@helix.nih.gov

Summary

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.

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