David, If you go to the Purdue web site and search the email archives using the terms "PMA" and "CD4" there are several in depth discussions of how PMA downregulates CD4 and various solutions to this problem. http://www.cyto.purdue.edu/hmarchiv/cytomail.htm Calman > ---------- > From: David Ritchie > Sent: Wednesday, October 16, 2002 14:48 > To: Cytometry Mailing List > Subject: CD4 on stimulated human T cells > > > Any suggestions welcomed on below problem, > > We are tracking the cytokine profiles (by intracellular staining) produced > by CD4+ T cells in patients who have undergone allogeneic bone marrow > transplant (BMT). We are looking at cytokine production pre- and > post-stimulation of T cells with PHA/ionomycin for 4 hours. We have no > difficulty clearly identifying CD4+ T cells on the unstimulated sample, > but > on the stimulated sample CD4 seems to disappear. CD3 is still clearly > evident. Has anyone seen this before? Is the cell fixing process used for > ic > staining likely to interfere with CD4 expression or anti-CD4 binding? We > don't seem to be losing cells in the short culture period. > > Thanks for any comments > > David Ritchie > >
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