We use CD20, CD22 and CD19 vrs FSC to identify abnormal B-cells in our
analysis gate to study light chain expression for monoclonality. We have
found that live gating for B-cells does not increase the sensitivity. We
just determine the % of B-cells in a specimen and ensure we acquire enough
B-cells for analysis. CD20 is also expressed at low levels on monocytes and
can obscure your study. We often use a sequence of analysis gates, for
example CD45 vrs SSC for lymphocytes followed by CD20 vrs FSC. That way we
can look at CD20+ non-monocytes. In bone marrow it is also useful to gate
out the pre B-cells (dim CD45) which are light chain negative when looking
for mature B-cell neoplasms. One must of course be careful when using
extensive gating (or any gating at all)to make sure that the neoplastic
cells are within your gate. We find the level of CD20, CD22 and CD19
helpful in detecting abnormal B-cells. For example the intensely bright
CD20 and CD22 of hariy cell leukemia or the dim CD20 of CLL.
Maryalice
>Hello everyone!
>
> I have developed a 3 color phenotyping method that is similar to CD45 gating
>using CD20 that is very good at "finding" very small populations of abnormal
>B-cells in bone marrow and blood. What I'd like to know is if anybody is
>using CD20 as a third color for gating on B-cells to diagnose B-cell
>leukemias for clinical purposes. I would greatly appreciate anyone's
>response to my inquiry. Thanks in advance.
>
>Hector Pulido
>Flowman@aol.com
Maryalice Stetler-Stevenson
Director Flow Cytometry Unit
Laboratory of Pathology, NCI, NIH
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