Just to add:
we seem to have a lot of endogenous biotin in liver, kidney and thyroid 
in additon to mast cells. And I use this egg white method from Dr. Miller 
with great success. You use the egg whites as source of avidin, and it is 
 very very cheap (2 egg whites in 200 ml solution only!). Dr. Miller (and 
another author before) said that you can use skimmed milk powder as 
source for biotin, however in Germany the concentration of biotin is not 
controlled in the milk, so we made the experience that sometimes it works 
and sometimes not. But probably in the US you can buy milk or milk powder 
 with an "exactly controlled biotin content".
Then when you use this egg whites, you do no need a protein block in 
addition.

Hope this helps.

Heike Grabsch, Germany


Cynthia Favara wrote:
> 
> Mark,
>         Don't know about endogenous biotin in mast cells would have to look
> that one up. However I attended a wonderful workshop by Dr. R Miller and he
> gave a protocol for blocking endogenouse biotin with egg whites. If you
> would like the particulars let me know and i will dig them out. There are
> also commercial products.
> Regards,
> Cynthia Favara
> NIAID/RML/LPVD
> 903 South 4th Street
> Hamilton, MT 59840
> PH: 406-363-9317
> FAX: 406-363-9286