Re: normal levels of HLA-DR on CD4
Howard Shapiro (hms@shapirolab.com)
Wed, 2 Apr 1997 21:35:10 -0500 (EST)
I couldn't agree more with your (Alice Givan's) recent comments on the
importance of quantification of activation antigens. In "normals", there
will be some variation in the number of circulating T-cells expressing any
particular activation antigen at any particular level because so-called
"healthy" people will have been exposed to different levels of subclinical
immunologic challenge before the blood sample was taken. However, many if
not most activation antigens are present at low levels on unstimulated
cells, and, as one uses more sensitive instruments and more specific
reagents, one will discern a higher fraction of "positive" cells. It makes
more sense to follow and report the median and percentiles (25th and 75th,
5th and 95th, or both) of numbers of antigens on defined subpopulations
(CD3+CD4+, CD3+CD8+, or even finer distinctions) than to express results in
terms of "positive" and "negative"; the only problems are 1)that we have to
reach consensus on quantification before we can start doing this, and 2)that
we'll have to recognize that data taken up to this point are of limited use.
-Howard