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Chronic Lymphocytic Leukemia

New Approaches for a Common Disease

CLL and Minimal Residual Disease (MRD)

Slide 24

October 2008

More questions regarding CLL and MRD.

Which specimen type should flow immunophenotyping studies be done on, peripheral blood or bone marrow?
I think the consensus in the community now is that blood is the preferred specimen as it is the easiest specimen to obtain. No studies have shown consistent and significant differences between blood and bone marrow.

To what detection level is MRD required in these cases?  
I would say the current expected level of MRD detection required is to 0.01%. To get to that level, we need to probably collect anywhere from 200,000 to 500,000 events by flow cytometry to be able to have enough B-cells to be able to analyze and interpret it with confidence.

Different Immunophenotypic approaches have been used including just simply CD5 versus CD19 versus 4-color vs. 6-color?
Multicolor adds specificity, but not necessarily sensitivity. Sensitivity is dependent on the cell mix and how many polyclonal B-cells are present. If there are very few polyclonal B-cells, a simple CD5 versus CD19 will work as several studies in the literature have shown. Challenges, however, arise when there is a mixture of monoclonal and polyclonal B-cells. In those situations, multi-color flow clearly provides diagnostic advantage.

Minimal Residual Disease (MRD)


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