Re: CD45-gating
Don Healey (dh100@mole.bio.cam.ac.uk)
Thu, 25 May 95 08:41:15 +0100
>Greetings,
>
>This question may be more philosophical than factual, and if it seems that I
>should know better, turn your burners to high.
>
>Assume that for immunophenotyping
>1) you use CD45 as a third color,
>2) you gate on CD45 vs SS, and
>3) you report results on the other two markers based on discrete CD45 vs SS
>bitmaps.
>
>Regarding the reporting of numerical values for CD45:
>1) isn't it nonsensical to report a value for CD45 when it itself is a bitmap
>parameter, or,
>2) doesn't it stand to reason that if you draw a bitmap around a discrete CD45
>population, that by definition that population is 100% "positive", and should
>be reported as such?
>
I agree that if a population is defined by a gate or region based on the
expression of marker, then it is assumed that all cells within that region
are, eg, CD45 +ve. This reflects the fact that you either do or don't
express CD45. However, this was an unfortunate choice for an example. Lets
take another.......Expression of an MHC molecule. An investigator may want
to study the scatter profile or 2nd marker expression on the brightest MHC
expressing cells. Under these conditions the investigator is setting a
subjective parameter. Therefore, it is necessary to state what fluorescence
characteristics were chosen for the gate, and what percentage of total MHC
+ve cells satisfied that criteria. This enables other investigators to
attempt to reproduce the same condtions on their machines.
How much information is given really depends on what is required to
reproduce a set of conditions on two machines operated by different
individuals, someone experienced in flow cytometry may not include data on
CD45 characteristics as he uses it regularly. But what about a Graduate
student who has no perception of the expected profile of CD45 on
lymphocytes???
Horses for courses I'm afraid!
Don
Snail to:
Dr Don Healey BSc. PhD.
BDA Research Fellow
Dept. of Pathology
Cambridge University
Tennis Court Road
Cambridge CB 1QP
TEL: 0223 333716
FAX: 0223 333914