Isotype Controls at
Sat Mar 30 10:24:36 EST 1996

Given that we are dealing with "not-normal" cells, how can we determine
/ predict what markers will be negative, assuming we can still define
"negative" as we have for years.  I have mixed emotions on this issue,
however; 1) 1000 leukemias and lymphomas should certainly provide a reliable
basis for determination, and therefore, since much of clinical phenotypic
analysis is pattern-comparison, isotypes are probably not necessary, 2) most
applications requiring more accurate negative-positive cutoff determinations
are done in research settings, and we can therefore continue to recommend
isotypes for use in that arena.  My concern lies in one of my original
statements; how do we define 'negative?'  What becomes our baseline?  I have
seen apparent predictively negative antibodies cause shifts in background
levels, and have often attributed this to differences in lots.  With more
stringent QC applied by antisera vendors, perhaps as required by CLIA, the
FDA, whoever. . . this is not so much a problem.  This means, however, that
we in flow facilities will have to become far more reliant on this vendor-QC,
rather than determining appropriate standards ourselves.  Is this where
clinical flow is headed. . . or am I wrong?
And. . . what about DNA/Imunofluorescence analysis (perhaps of questionable
clinical utility, but we do it)?  What do we do about this?

It's interesting to note that these issues have been debated for years, both
for immunofluorescence and DNA content/ploidy standardization, and also
that guidelines have been proposed (I know I've seen them somewhere. . .), but
we continie to revisit these questions.  


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