Its well known that PMA causes transient downregulation of CD4. I don't have a reference at my fingertips but if you do a pub med search on CD4, T cells, and PMA and look in the 80s/ early 90s you'll find it. This btw is the opposite result from antigen mediated stimulation of t cells which after 24-72 hours causes CD4 to be upregulated. --On Thursday, October 17, 2002 7:48 AM +1300 David Ritchie <dritchie@malaghan.org.nz> wrote:r > > 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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