Hi All,
I've been working on developing monoclonals to carbohydrate antigens. One in particular has given some interesting results. Initially all we could produce was IgMs to this antigen (As is the case with alot of these antigens). After developing a method of presenting this antigen to mice we produced a strong IgG response and after a fusion the first IgG1 to this antigen.
This IgG1 will outcompete any of the IgMs/IgG3s we have for binding to the epitope. The IgG1 however has an extremely high-offrate compared to the IgMs
which once attached bind strongly. - In my experience (and in general) IgG1s have a higher affinity than that of IgMs - but not in this one.
I have one theory - The actual protein which has the Carbohydrate epitope is around 300 Kda and has heaps of these carbohydrate epitopes on it. I've talk to some protein experts who have said it is likely that the sugar epitopes are probably
slightly different across the whole structure. Which has led me to believe that maybe why the IgMs have a lower offrate is that they can get more arms onto the varying sugar epitopes - hence bind better thus have a higher affinity because the can bind to more than one site.
If anyones got any other Ideas - I'd be glad to hear them.
Regards
Chris Weir
BTF
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