HLA B27 TYPING
Tom Sawyer (TSAWYER@gemini.mco.edu)
Thu, 17 Apr 1997 17:19:00 -0400 (EDT)
Greetings, Our experience with B27 by flow is very similar. There does not
appear to be a truely monospecific antibody on the market. In a study of over
100 patients performed by flow and microcytotoxicity we obtained 4 false
positives and zero false negatives using one lambda's antibody. We however are
not able to confirm that this is due to cross-reactivity with B44. To the best
of my knowledge one lambda does not acknowledge this problem. This is
particularly disturbing since their reagent has been FDA approved for stand
alone testing. The problem with the reagents is clearly demonstrated in the
results of the first two CAP proficiency testing samples of 1996. In these
surveys, 33% and 49% of the laboratories incorrectly indentified a specimen
(HLA-A1;B37,57(Bw4)) as positive by flow cytometry. This clearly demonstrates
the need to confirm all suspected positve flow specimens by an alternate
method.
Tom Sawyer
Medical College of Ohio
(419) 381-4212
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