What is flow cytometry?

Flow cytometry is also an incredibly fancy
and cool test.

It's really a little bit older than
the MRD assays that we're talking about.

I have to give credit to this couple,
Len and Leonore Herzenberg,

who worked at my old institution,
Stanford, for many, many decades,

and they invented the flow cytometer

and they invented the first one
with all the tubes and wires

and everything,
just to tell you how cool it is.

Basically, what it is in real life
is we passed lots of cells one by one,

by one by one

in front of a laser, and then the
laser refracts off of each cell singly.

And you can interpret
ten or 20 things about each cell.

So the most obvious thing would be

if it's a CLL cell or a 
regular healthy blood cell.

So flow cytometry is very important
in first diagnosing CLL

and some other types
of leukemias, lymphomas as well.

And it also can be used sort of as an MRD assay, 
like that other MRD test, the clonoSEQ, that we talked about

It’s not quite as sensitive as the MRD test.

The flow cytometry could probably pick up
like one CLL cell out of 10,000 cells,

whereas that MRD clonoSEQ 
assay can pick up one cell

out of a million cells.