Re: pulse width

James Weaver 301-594-5879 FAX 301-594-3037 (WEAVER@cder.fda.gov)
Tue, 30 Jul 1996 16:55:51 -0400 (EDT)

Part of the complexity here is that the cells do not have a smooth
surface (which affects FS) and they do not have similar granularity
(which affects SS). The combination of these two factors is what
allows us to do fair groupings based on scatter alone. The use of
light scatter to estimate cell size can be very deceptive. A few
years ago I attempted to use light scatter to estimate cell volume
changes. I had both flow data and Coulter Volume data for the same
cells under the same conditions. For both lymphoid and fibroblastoid
cell lines no change is observed in SS in spite of 30% increases in
cell volume. With lymphoid cells but not fibroblastoid cell lines,
the FS signal DROPS when cell volume increases. A possible
explanation for this reversal of the expected response is that
lymphoid cells have many villi on the surface which makes them very
efficient at light scatter. When the cells swell, the villi are
reduced or eliminated and the cell becomes much less effective at
light scatter. Some of this data has been published recently (Weaver
et al, Am. J. Physiol: Cell Physiol. 270 (Cell Physiol. 39)
C1453-C1460 (1996)). Hope this helps with your question.

-Jim Weaver

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