Isotype controls

Florence Harrod fharrod at
Wed Mar 27 18:55:37 EST 1996

Isotype controls
Dear Cytometrists:
With regard to the search for a better negative control for flow cytometry and
other antibody based assays, two solutions come to mind:  One is to block the
antibody's specific binding with soluble antigen.  This is practical in limited
cases.  For example, when using antibodies to detect intracellular cytokines,
the best negative control is to use the soluble cytokine for blocking of the
specific staining.  Unfortunately, this may cost more than using isotype
controls, a separate control has to be used for each antibody, and it is
impractical for most cell surface markers.  The second, similar, approach would
be to use Fc's of your specific antibody as a negative control.  That's probably
impractical, too!  Each lab has to choose for itself whether they will use the
BEST possible negative controls for their studies, even though they may cost
more in effort, time and/or money.  Since the ideal is often unattainable, many
have had to "settle" for isotype controls.  But anyone using isotype controls
should be aware of the inherent problems with this technique when interpreting
the data.  
Florence Harrod

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