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This is actually not as easy as it should be. We have played for
years trying to find something which is really comprehensive and
specific. The IL-2 receptor alpha and beta chains should be the
best, but in our experience are often expressed at quite low levels
on cells activated in vivo. CD69 is a good early marker, HLA class
II is virtually useless. We find the best surface marker for in vivo
activated cells to be CD71, the transferrin receptor, this is
expressed by all dividing cells, as they require exogenous iron to
activate the ribonucleotide reductase enzyme during DNA synthesis.
It appears in late G1, peaks in S and is maintained through G2 and M.
Obviously you need to double label for a T cell marker (usually
CD4/CD8 or CD2 because the TCR/CD3 complex can be down-regulated on
activated T cells. If you don't mind fixing the cells I would
recommend doing a proper cell cycle analysis with PI or 7-amino
actinomycin-D (the latter has the advantage of not needing DNAse
treatment).
Have fun
Mike
...........................................................
Mike Salmon
Department of Rheumatology
The Medical School
University of Birmingham
Birmingham B15 2TT
United Kingdom
Tel: 44 (0)121 414 6780
Fax: 44 (0)121 414 6794
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