RE: Why don't all cells stain?

Hi Mark,
 
al lot more info would be needed to answer that question. What's the sample
(primary cells/cell line/clone), what's the type of marker (internalizing),
what staining conditions...?
 
One comment though: two-colour stainings may result in decreased positivity
for either marker versus single staining the same markers with the same
antibodies, if the two are competing for binding (same epitope or close
enough to cause steric hindrance).
 
Guy
 



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-----Original Message-----
From: Mark D'Amico [mailto:MDAmico@panaceapharma.com] 
Sent: Wednesday, October 26, 2005 2:08 PM
To: cyto-inbox
Subject: Why don't all cells stain?


I have been working with flow for a while now, off and on. I have always had
this question. When I probe with an antibody to an extracellular epitope, or
when I do two color, only a portion of the cells stain positive. Why is
this? Shouldn't all the cells stain positive for an expressed antigen in
solution with antibody in excess? 
 
Thanks.
 
Mark D'Amico, Ph.D.
Scientist
Panacea Pharmaceuticals
207 Perry Parkway    #2
Gaithersburg, MD   20877
(240) 243-8000 Ext. 206
mdamico@panaceapharma.com
 


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