Is binding antibody all neutralizing antibody?

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Philipp
Philipp's picture
Is binding antibody all neutralizing antibody?

Hello everyone!

I'm screening neutralizing antibodies by using B-cells, specially what's called ASC against a antigen on a microarray chip and phage-display.
This might be the issue about if the screened antibodies which are enable to bind the antigen during screening but I'm not sure if the bound one could be functional as neutralizing antibodies at the end.
What's the idea?
As one knowing almost nothing about the cencept - what's the neutralizing antibody?, I need your help to add your opinions to me.
As I know, there'd be some false-positives during selection or some existable mistakes during experiments, but beyond such exceptions, theoritically I want to ask you what the neutralizing antibodies are.

So, Is binding antibody all neutralizing antibody? Otherwise, what binds well could be just binding but possibly could be not always the neutralizing ones....

Thanks!

   - Philipp Huh

Sami Tuomivaara
Sami Tuomivaara's picture
Philipp,

Philipp,

All antibodies that have at least some affinity to some molecule are binding antibodies, by definition. Those binding antibodies that bind the target molecule such a way to affect its biological function are called neutralizing antibodies.

If you antigen is very small (approximately same size or smaller than antibody binding site), any binding antibody is highly likely to be neutralizing antibody as well, since the antibody binding site "swallows" the whole or most of the molecule and thus neutralizes its function.

On the other hand, if your target molecule is very large (large protein), there are large number or potential antigenic sites where different antibodies can bind. Some or most of those antibodies bind to a surface site which does not have direct biological function. Those antibodies that bind to a surface site that has binding/catalytic/some other function, block this function and are called neutralizing antibodies.

It is likely that your microarray chip screening produces lot of hits, some of which are not neutralizing. But to screen large number of cell lines and antigens, this is a necessary step, since you eliminate all non-binding antibodies, which are then non-neutralizing as well. Most likely functional assay screen is needed for the positive hits, to separate neutralizing antibodies from your generic binding ones.

The affinity (quantitative binding) of antibody has of course role as well, besides the obvious qualitative yes/no binding question. Even if the binding site is on a catalytic site, the affinity between the antibody and the antigen has to strong enough, or else the binding might not have measurable effect on the function.

Cheers,