Isotype Cross-Reactivity

Mike Clark mrc7 at
Tue Oct 1 06:23:10 EST 2002

In article <66becbd5.0209301205.5a01b2f7 at>, Daniel Rosen
<URL:mailto:daffyduck1945 at> wrote:
> Hi,
> This is probably a very basic question, but what could cause isotype
> cross-reactivity in antibodies?  I'm trying to raise rabbit anti-mouse
> IgG antibodies by injecting the rabbit with whole mouse IgG (H&L), but
> find that the antibodies are also reactive to the other isotypes.
> Is this because I'm using whole mouse IgG and the antibody recognizes
> the light chains of other antibodies?

Almost certainly yes. You also have V-region epitopes which would be shared
with other classes and subclasses.

> What should I do instead?  Use only the gamma chain?

That is one method but you might not get specificity for native epitopes.

> Is there a way to extract just the IgG antibodies?

Yes the method is to pre-adsorb your antisera on the isotypes you don't
want to detect. You could also combine this with affinity purification on

> Thanks to all who reply!
> Dan

Mike Clark,                        <URL:>
 o/ \\    //          ||  ,_ o   M.R. Clark, PhD. Division of Immunology
<\__,\\  //  __o      || /  /\,  Cambridge University, Dept. Pathology
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