Many years ago Philippa Marrack, John Kay and the
author of this message were graduate students in a
Cambridge laboratory. The latter two were attempting to
compare the spectrum of genes expressed at the RNA level
of activated and "resting" peripheral blood mononuclear
cells. These studies have continued since, and much has
been learned.
Now, the interesting paper of Teague et al. (Proc. Natl. Acad.
Sci. 96, 12691, October 1999) from the Marrack laboratory
compares the spectrum of genes expressed at the RNA level
of "resting" mouse T cells with the same cells 8 hr after
activation. Using powerful Affymetrix gene array technology
the results are spectacular, but do not appear to take into
account the fact that isolation procedures themselves may
change lymphocyte gene expression.
Whether these isolation procedures simulate some
naturally occurring process is uncertain.
What is certain, is that we must be very cautious
in declaring these cells to be "resting", in the sense that
they have not been stimulated in some way. Kay, Forsdyke and
their coworkers found that overnight preincubation
returned cells to a state which might be related to the in vivo
"resting" state (low expression of c-fos/G0S7 and Egr1/G0S30).
Following activation greatly increased expression then occurs.
I append some references below:
Donald Forsdyke
Discussion Leader. Bionet.immunology
Heximer, S.P., Cristillo, A.D., Russell, L. and Forsdyke,
D.R. (1998) DNA Cell Biol.17, 249-263. Expression and
Processing of G0/G1 Switch Gene 24 (G0S24/TIS11/TTP/NUP475)
RNA in Cultured Human Blood Mononuclear Cells.
Cristillo, A.D., Heximer, S.P., Russell, L., and Forsdyke,
D.R. (1997) DNA Cell Biol. 16, 1449-1458. Cyclosporin
A Inhibits Early mRNA Expression of G0/G1 Switch Gene 2
(G0S2) in Cultured Human Blood Mononuclear Cells.
Heximer, S. P., Cristillo, A. D. & Forsdyke, D. R.(1997)
DNA Cell Biol. 16, 589-598. Comparison of mRNA expression of
genes regulating G-protein signalling (RGS1/IR20/BL34 and
RGS2/G0S8) in cultured human lymphocytes.
http://post.queensu.ca/~forsdyke/theorimm.htm
