Dear Shannon,

I have found papain to be useful for IHC. Suppliers of blood banking
reagents usually carry  stabilised preparations of this enzyme. Effective
digestion of ffpe sections is complete in 5 min. at room temp. Many
antibodies are enhanced using this pretreatment (eg cytokeratins, many CDs,
class I MHC, kappa/lambda). Some antigens are destroyed eg CD34, meaning the
enzyme can also be used for QC on certain primary antibodies, ie negative
control without omission or substitution of primary.
Why use such a large volume?

hooroo, richard hazelton