Ig titers--are there standards?

Tom Barr mdp96tab at shef.ac.uk
Thu Jul 20 16:06:42 EST 2000


Russ,
    I assume your talking about determining titre by ELISA, and if so I offer
the following advice. Titres will vary wildly between tests as conditions are
never the same and different scientists will perform the tests with slight
differences. Different antigens could also be in use (and certainly different
batches). Values are normally obtained from a comparison with normal (non
immune) serum (i.e. a titre of 256 would indicate the dilution at which
experimental sera has a Ig level comparable to normal serum). In this case you
guess correctly; the standard varies.
    It would only be possible to convert a titre to an actual concentration if
a positive control of known concentration was included with each test. This is
in unlikely, unless you have a mAb or quantified antiserum against the antigen,
and at best would give only an approximate value.
    Hope that was of some use...

Cheers,

Tom
-----------------------------------------------
Tom Barr (mdp96tab at shef.ac.uk)
Division of Molecular and Genetic Medicine (F-Floor)
University of Sheffield Medical School
Beech Hill Road
Sheffield
S10 2RX


Russ wrote:

>         In the process of studying Chlamydophila pneumoniae, I have found
> that of IgA, IgG, and IgM titres used by various researchers to determine
> the state of infection varies greatly. IgG titers ranging from 16 to 512
> have been used by various researchers.
>         My guess is that different tests have different standards.The
> researchers probably decide to use higher or lower thresholds depending on
> what they are trying to learn.
>         Are there any standards for interpreting Ig levels? Any tables to
> convert results obtained with test Y to the corresponding results in test Z?
> Thanks for your attention.
>
> Russ Farris










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