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E.R.I.C. 2018 Meeting: Professor John Seymour on MBL (Monoclonal B-cell Lymphocytosis), a CLL (chronic lymphocytic leukemia)

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At the first International European Research Initiative on CLL (ERIC) meeting held in Barcelona, Spain, there was much talk about MBL or Monoclonal B-cell Lymphocytosis, a possible precursor to CLL.

I asked Dr. John Seymour of the PeterMac in Melbourne, Australia to explain the basic concepts.


  • All cancer including CLL is clonal, in other words, it is made up of identical cells.
  • If one has ≥5,000 monoclonal B-cells that are typical of CLL, then chronic lymphocytic leukemia can be diagnosed.
  • If one has < 5,000 monoclonal B-cells,  the diagnosis is MBL.
  • The clonal cells in both diagnoses are the same and the 5,000 value is admittedly arbitrary.
  • MBL consist of two groups:
    • Low-count MBL has blood B-cell counts <0.5x9 cells/liter.
    • High-count MBL has blood B-cell counts ≥0.5x9/L but <5×109/L.
    • Low-count MBL does not progress to malignant disease.
    • High-count MBL does progress at a rate of 1-2% per year.
  • Both MBL and CLL patients have impaired immunity that puts us at a higher risk for infections and cancer.
  • Even when diagnosed with CLL, many of us can have a normal life expectancy.

Please enjoy my interview from ERIC 2018 with Dr. John Seymour.

Here is a 2015 lecture that Dr. Kay gave on MBL and early care in CLL:

Thanks for watching and reading.

Brian Koffman MDCM (retired)