RE: conjugation vs. sandwich

From: Tom Mc Closkey (thomasm@nshs.edu)
Date: Fri Mar 28 1997 - 15:43:23 EST


--- On Thu, 27 Mar 1997 00:06:24 -0500 (EST)  Dave Novo 
<novod@muss.cis.mcmaster.ca> wrote:

 I was wondering what people 
>thought of the relative merits of 
>conjugating FITC to the antibody myself   vs.
>buying a generic anti IgG-FITC premade conjugate and using a sandwich 
>type technique. 
>
>What are the pro's and cons of the various ideas?
>
I think the choice will be determined by the experimental question being 
asked.

Directly conjugated antibodies are useful in multicolor labelling, are 
easier [one step] and good if low cell number might be a problem [less 
washes].  Remember, depending on the antigenic densityl of the marker in 
question, you will probalby also need to conjugate an isotype Ab to assess 
background labelling.

Indirect labelling works well for a single color assay [can be used in 
multicolor but not as simple].  It is probably easier to control for 
backgoround with an indirect assay [use an isotype cont and the same 2ndary 
you use for your test sample].  Also, you have a choice of colors for the 
GAM reagent and you may want to use something "brighter" than FITC, 
depending on the resolution between your positives and negatives.  All else 
being equal, an indirect labelling procedure will tend to amplify your 
signal as well.

Good luck,
Tom

--------------------------------------------------------
Thomas W. Mc Closkey, Ph. D.
Director, Flow Cytometry
North Shore University Hospital
Biomedical Research Center
350 Community Drive
Manhasset, Long Island, New York 11030
ph: 516-562-4844 [office]; 516-562-1135/4641 [lab]
3/28/97   12:52:08 PM
E-mail: thomasm@nshs.edu 
--------------------------------------------------------



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