RE: HLA TYPING B27 BY FLOW
Snider Denis (sniderd@fhs.csu.mcmaster.ca)
Mon, 21 Apr 1997 16:31:17 -0400
Vivian's experience is basically the same as ours with the B-D kits. We
are a regional testing center for B27 and use the kit to screen the
200-300 samples per month. From initial pilot data we developed a
screening scheme for "gray-area" flow results representing B27
fluorescence intensities near the B-D "cut-off" channel number (+/- 6
channel numbers). Those within this range represent about 10% of our
samples, and we immediately send these to cytotoxicity or DNA typing for
confirmation. Of those only 50% turn out to be false positive or
negative (cytotoxicity as "gold" standard), with about equal
distribution of negatives and positives. Of false positive, 75% are B7+
(cytotoxicity or DNA). Since this represents only 2% of our work load,
it does not make sense to further test for B7 in flow. The false
negatives are not easily explained although some relate to overall loss
of class I expression, tested in flow using the W6/32 mAb. In all, the
B27 results are >95% accurate, and fairly inexpensive (even by B-D
standards of inordinate cost!!!), compared to cytotoxicity alone or
testing in conjunction with SSP DNA.
As I see it the cytotoxicity tests have never been examined to a
reliability of 95% so some of the "discrepancies" could be related to
variability in the cytotoxicity accuracy in a given laboratory.
So for large volume, the B-D reagents are economical and a very reliable
screen. In the tough cutback times for Health Care in southern Ontario,
that has a "real" meaning. Of course, if you expect to have a large
volume such as ours, you should try to "extract" a little compensation
in reagent cost from B-D.
Good luck,
Denis Snider
>
CD-ROM Vol 3 was produced by Monica M. Shively and other staff at the
Purdue University Cytometry Laboratories and distributed free of charge
as an educational service to the cytometry community.
If you have any comments please direct them to
Dr. J. Paul Robinson, Professor & Director,
PUCL, Purdue University, West Lafayette, IN 47907.
Phone: (765)-494-0757;
FAX(765) 494-0517;
Web
http://www.cyto.purdue.edu
, EMAIL
cdrom3@flowcyt.cyto.purdue.edu
