Both the UK and Italian groups have subsequently performed further studies of MBL in the general population with a focus on biological investigations.(4, 5) Of note the second Italian study utilized a higher sensitivity flow cytometry approach and identified a higher prevalence (7.4%) of MBL in the general population than in the primary care cohort.(8) An even more recent study from Salamanca utilized the highest sensitivity flow cytometry approaches available to analyze 5 million peripheral blood cells per individual. Using this strategy the investigators identified a very high prevalence of CLL phenotype cells in the general population which were detectable in more than 1 in 5 individuals over 60 years old.(9) As indicated by the latter two studies, the differences in reported prevalence of MBL across series are most likely due to differences in the sensitivity of the flow cytometry approach applied. In particular, the Salamanca group screened at least ten times more cells (5 million per case vs. 200,000 – 500,000) and used 8- color staining panels as compared to the previously used 4-color(5) and 5-color(8) protocols. The percentage
