Re: Fc Blocking
Mike Clark (mrc7@cam.ac.uk)
Wed, 18 Jun 1997 09:34:36 +0100 (BST)
On Tue 17 Jun, Richard K. Meister wrote:
>
> Greetings, everyone:
>
> I am in need of a method to block Fc receptors on human cells. We have
> antibodies (whole molecule) against a ligand on the surface of certain cells
> that we want to use to block binding of those cells to their target - a
> receptor on a human macrophage cell line. However, we need to prevent
> binding to the Fc receptors on the macrophages via the Fc portion of our
> antibodies. We prefer not to have to make F(ab')2 fragments of all of the
> antibodies we will be testing.
>
> I know that anti-CD16/32 monoclonals are available to block Fc receptors in
> the mouse, but as far as I have been able to find out, the anti-human CD16
> and CD32 monoclonals are not efficient as blocking agents.
>
> If you have an efficient method of blocking human Fc receptors, please let
> me know. And, thanks in advance.
>
IgG antibodies from several species bind human FcgR with good affinity and
hence will block the Fc binding of your antibody. I don't know what
detection system you are using, direct or indirect, or which species your
antibody is. However if for example your antibody is a rat or mouse
monoclonal you could block Fc binding using 5-10% heat inactivated normal
Rabbit serum in your antibody dilution buffer. There are no IgG subclasses
in rabbit so all the IgG binds competitively the human FcgR.
Alternatively if your specific antibody is rabbit you could block with rat
or mouse IgG. I would use irrelevant (ie non anti-human cells) monoclonals
of the mouse IgG2a or rat IgG2b subclasses by choice. Again 5-10% heat
inactivated ascitic fluid by choice.
Mike Clark, <URL:http://www.path.cam.ac.uk/~mrc7/>
--
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