 |
 |
 |
 |
If fluorescence intensity is only proportional to antigen density at
saturating amounts of antibody, why is the G2&M/G1 ratio 2? If not
exactly 2, it's very close. Which is pretty amazing considering the
geometry of the detection system and a few zillion other factors. While
cell cycle analysis is generally measured with DNA staining at equilibrium
the DNA stain is never at saturation. I've only looked out to 2mg/ml PI
and the cells were brighter than the 1mg/ml (yes, I said MILLIGRAMS). Even
without equilibrium the G2&M/G1 relationship is approximately maintained;
data not shown, but anyone looking at HO342 in viable cells can attest.
I'm sure the difference in diffusion coefficients between a protein and a
small dye molecule are substantial but I don't see how this would prevent
immunofluorescence from being proportional to antigen density at
sub saturating concentrations. I'm sure somebody out there can set me
straight.
Too bad the discussion comparing the FACSCalibur and the XL fizzled into
an argument about sensitivity. One would think a major factor in evaluating
an instrument would be the availability and cost of reagents, or the computer
platform and software. So many things to consider.
Along those same lines, I'm surprised there was little or no discussion on
this mailing list about the article in Communications in Clinical Cytometry
(vol.22, No.3, 232-242) concerning "instrument-dependent fluorochrome
sensitivity". At one point I heard rumors of litigation. I wasn't shocked
by the article as much as the fact that it was published.
td
Early one morning the sun was shining, I was laying in bed
wondering if she'd changed it all or if her hair was still red.
- BD
-- ============================================================================== Thomas Delohery | Internet: t-delohery@ski.mskcc.org Manager, Flow Cytometry Core Facility | Phone: (212) 639-8729 Memorial Sloan-Kettering Cancer Center | Fax: (212) 794-4019 1275 York Ave. Box 98 | New York, NY 10021 | ==============================================================================
|
|
|
|