syphilis serology

Pete Kwasowski P.Kwasowski at surrey.ac.uk
Mon Sep 30 06:19:48 EST 1996

At 02:19 30/09/96 -0700, you wrote:
>Over the last year we have found a number of sera that were moderately
>positive for TPHA, weak positive FTA and negative for reaginic tests.
>Although confirmed on retesting, after freezing and thawing the sera became
>negative.  We are using the kit marketed in England by Launch as the
>'reditest'.  I have encountered this problem a few times previously but now
>it seems much more frequent.
>Has anybody else experienced this, or got any views?
>Steve Barrett
>Dr. S.P. Barrett,
>Microbiology Department,
>St. Mary's Hospital
>Praed St.,
>Phone UK 01717251572
>Fax   UK 01717251856

I've no idea about the specifics of your test, however, loss of titre post
freeze/thawing makes me think that you're loosing IgM immunoreactivity in
your samples.

We have found this with early bleeds after priming immunizations when making
polyclonal antisera. Which is one of the reasons we store our antisera at 4
deg C with azide, rather than frozen.

Just my "two bob's worth".


Dr P Kwasowski
ClifMar Associates Limited
School Biological Sciences
University of Surrey
Guildford, GU2 5XH
United Kingdom

Tel/FAX: +44 (0)1483 259708
E-mail: P.Kwasowski at surrey.ac.uk

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